485BPOS

As filed with the Securities and Exchange Commission on January XX, 2013

File Nos. 2-91312, 811-04033

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 54	¨

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 55	¨

SIT MUTUAL FUNDS II, INC.

(Exact Name of Registrant as Specified in Charter)

3300 IDS Center, Minneapolis, Minnesota 55402

(Address of Principal Executive Offices) (Zip Code)

(612) 332-3223

(Registrants’ Telephone Number, including Area Code)

Kelly K. Boston, Esq.

Sit Mutual Funds

3300 IDS Center

Minneapolis, Minnesota 55402

(Name and Address of Agent for Service)

Copy to:

Michael J. Radmer, Esq.

Dorsey & Whitney, LLP

50 South 6^th Street, Suite 1500

Minneapolis, Minnesota 55402

It is proposed that this filing will become effective (check appropriate box):

x immediately upon filing pursuant to paragraph (b) of rule 485

¨ on (specify date) pursuant to paragraph (b) of rule 485

¨ 60 days after filing pursuant to paragraph (a)(1) of rule 485

¨ on (specify date) pursuant to paragraph (a)(1) of rule 485

¨ 75 days after filing pursuant to paragraph (a)(2) of rule 485

¨ on (specify date) pursuant to paragraph (a)(2) of rule 485

If appropriate, check the following box:

¨ This post-effective amendment designates a new effective date for a previously filed post effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant has duly caused this Registration Statement on Form N-1A to be signed on its behalf by the undersigned, thereunder duly authorized, in the City of Minneapolis, State of Minnesota, on the XX day of January 2013.

SIT MUTUAL FUNDS II, INC.
(Registrant)
By	/s/ Roger J. Sit
	Roger J. Sit, Chairman

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to the Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the dates indicated. The enclosed Amendment does not contain disclosures that would render it ineligible to become effective pursuant to Rule 485(b).

Signature and Title
/s/ Roger J. Sit	Dated: January XX, 2013
Roger J. Sit, Chairman
(Principal Executive Officer)
/s/ Paul E. Rasmussen	Dated: January XX, 2013
Paul E. Rasmussen, Treasurer
(Principal Financial Officer and Accounting Officer)
William E. Frenzel, Director*
Edward M. Giles, Director*
Sidney L. Jones, Director*
Bruce C. Lueck, Director*
Donald W. Phillips, Director*
Barry N. Winslow, Director*
By /s/ Roger J. Sit	Dated: January XX, 2013
Roger J. Sit, Attorney-in-fact
*Pursuant to a power of attorney filed previously   with the Commission.

EXHIBIT INDEX

Index No.	Description of Exhibit
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-1-1.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Sit Quality Income Fund

SUMMARY INFORMATION

INVESTMENT OBJECTIVE

The Fund seeks high current income and safety of principal.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	Sit Quality Income Fund
Shareholder Fees (fees paid directly from your investment)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Sit Quality Income Fund
Management Fees	0.90%
Total Annual Fund Operating Expenses	0.90%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated (with reinvestment of all dividends and distributions), that your investment has a 5% return each year, that the Fund’s operating expenses remain the same, and that you redeem all of your shares at the end of those periods. Although your actual costs and returns may differ, based on these assumptions your costs would be:

Expense Example (USD $)	1-Year	3-Years
Sit Quality Income Fund	92	288

PORTFOLIO TURNOVER

The Fund pays transactions costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses in the example, affect the Fund’s performance. The Fund’s inception date was December 31, 2012 therefore there is no turnover rate to report.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its objective by investing under normal market conditions at least 80% of its assets in debt securities issued by the U.S. government and its agencies, debt securities issued by corporations, mortgage and other asset-backed securities.

The Fund invests at least 50% of its assets in U.S. government debt securities, which are securities issued, guaranteed or insured by the U.S. government, its agencies or instrumentalities. The balance of the Fund’s assets will be invested in investment grade debt securities issued by corporations and municipalities, and mortgage and other asset backed securities. Investment grade debt securities are rated at the time of purchase within the top four rating categories by a Nationally Recognized Statistical Rating Organization or of comparable quality as determined by the Fund’s investment adviser (the “Adviser”). The Fund’s dollar-weighted average portfolio quality is expected to be “A” or better.

The U.S. government securities in which the Fund will invest include direct obligations of the U.S. Treasury and securities issued or guaranteed by federal agencies or authorities and U. S. government-sponsored instrumentalities or enterprises. The Fund will invest in pass-through securities. Pass-through securities include mortgage-backed securities such as those issued by Government National Mortgage Association (GNMA), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC). GNMA is an agency of the U.S. government and its securities are backed by the full faith and credit of the U.S. government. FNMA and FHLMC are U.S. government sponsored enterprises and their securities are backed by their credit.

The Fund may invest in securities that have not been registered for sale under the Securities Act of 1933 pursuant to Rule 144A (Rule 144A securities) which are determined to be liquid by the Adviser. The Fund may seek to hedge the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets.

In selecting securities for the Fund, the Adviser seeks securities providing relatively high current income. In making purchase and sales decisions for the Fund, the Adviser considers its economic outlook and interest rate forecast, as well as its evaluation of a security’s credit quality, yield, maturity, liquidity and the security’s sector. The Adviser attempts to maintain an average effective duration for the portfolio of approximately 0 to 2 years. The Adviser’s duration target within this range is based on its interest rate forecast. Duration is a measure of total price sensitivity relative to changes in interest rates. Portfolios with shorter durations are typically less sensitive to changes in interest rates.

PRINCIPAL INVESTMENT RISKS

As with all mutual funds investing in bonds, the price and yield of the Fund may change daily due to interest rate changes and other factors. You could lose money by investing in the Fund.

The principal risks of investing in the Fund are as follows:

• Call Risk: Many bonds may be redeemed (“called”) at the option of the issuer before their stated maturity date. In general, an issuer will call its bonds if they can be refinanced by issuing new bonds which bear a lower interest rate. The Fund would then be forced to invest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income.

• Credit Risk: The issuers or guarantors of securities (including U.S. government agencies and instrumentalities issuing securities that are not guaranteed by the full faith and credit of the U.S. government) owned by the Fund may default on the payment of principal or interest, or the other party to a contract may default on its obligations to the Fund, causing the value of the Fund to decrease.

• Income Risk: The income you earn from the Fund may decline due to declining interest rates.

• Interest Rate Risk: An increase in interest rates may lower the Fund’s value and the overall return on your investment. The magnitude of this decrease is often greater for longer-term fixed income securities than shorter-term securities.

• Liquidity Risk: The Fund may not be able to pay redemption proceeds within the time periods described in this Prospectus because of an inability to sell certain debt securities with more limited trading opportunities at a favorable price or time. Recent events have caused the markets for some debt securities to experience lower valuations and reduced liquidity. Consequently, the Fund may have to accept a lower price to sell a security, sell other securities to raise cash, or give up an investment opportunity, any of which could have a negative effect on the Fund’s performance. Infrequent trading may also lead to greater price volatility.

• Management Risk: A strategy used by the investment management team may not produce the intended results.

• Market Risk: The market value of securities may fall or fail to rise. Market risk may affect a single issuer, sector of the economy, industry, or the market as a whole. The market value of securities may fluctuate, sometimes rapidly and unpredictably.

• Mortgage and Asset-Backed Securities Risk: The value of these securities may be adversely affected by factors including changes in interest rates, the market value of the underlying assets, and the creditworthiness of the issuer or entities that provide credit enhancements. These securities are subject to prepayment risk and the impact of prepayments on the value of these securities may be difficult to predict and may result in greater volatility.

• Prepayment and Extension Risk: Declining interest rates may compel borrowers to prepay mortgages and debt obligations un- derlying the mortgage-backed securities owned by the Fund. The proceeds received by the Fund from prepayments will likely be reinvested at interest rates lower than the original investment, thus resulting in a reduction of income to the Fund. Likewise, rising interest rates could reduce prepayments and extend the life of securities with lower interest rates, which may increase the sensitivity of the Fund’s value to rising interest rates.

• Reinvestment Risk: Income from the Fund’s debt securities portfolio will decline if and when the Fund invests the proceeds from matured, traded or called securities in securities with market interest rates that are below the current earnings rate of the Fund’s portfolio.

• Rule 144A Securities Risk: The value and liquidity of these securities may be adversely affected in the event that the number of qualified institutional buyers interested in purchasing 144A securities is limited, the Fund might be unable to dispose of such securities promptly or at reasonable prices, and they may be subject to greater volatility.

• U.S. Government Securities Risk: Securities purchased by the Fund issued by Fannie Mae and Freddie Mac are neither issued nor guaranteed by the U.S. Treasury and, therefore, are not backed by the full faith and credit of the United States. There is a risk that the U.S. government will not provide financial support to U.S. government agencies or instrumentalities if it is not obligated to do so by law.

• Valuation Risk: The Fund may hold securities for which prices from pricing services may be unavailable or are deemed un- reliable, in which case the Fund’s procedures for valuing investments provide that the Adviser shall use the fair value of such securities for valuing investments. There is a risk that the fair value determined by the Adviser or the price determined by the pricing service may be different than the actual sale prices of such securities.

HISTORICAL PERFORMANCE

The Fund’s inception was December 31, 2012 and therefore there is no performance information to report at this time. For current performance information, call 1-800-332-5580 or visit www.sitfunds.com. The Fund’s past performance does not necessarily indicate how it will perform in the future.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	SIT MUTUAL FUNDS II INC
Prospectus Date	rr_ProspectusDate	Dec. 31, 2012
Sit Quality Income Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	SUMMARY INFORMATION
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks high current income and safety of principal.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transactions costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses in the example, affect the Fund’s performance. The Fund’s inception date was December 31, 2012 therefore there is no turnover rate to report.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated (with reinvestment of all dividends and distributions), that your investment has a 5% return each year, that the Fund’s operating expenses remain the same, and that you redeem all of your shares at the end of those periods. Although your actual costs and returns may differ, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its objective by investing under normal market conditions at least 80% of its assets in debt securities issued by the U.S. government and its agencies, debt securities issued by corporations, mortgage and other asset-backed securities. The Fund invests at least 50% of its assets in U.S. government debt securities, which are securities issued, guaranteed or insured by the U.S. government, its agencies or instrumentalities. The balance of the Fund’s assets will be invested in investment grade debt securities issued by corporations and municipalities, and mortgage and other asset backed securities. Investment grade debt securities are rated at the time of purchase within the top four rating categories by a Nationally Recognized Statistical Rating Organization or of comparable quality as determined by the Fund’s investment adviser (the “Adviser”). The Fund’s dollar-weighted average portfolio quality is expected to be “A” or better. The U.S. government securities in which the Fund will invest include direct obligations of the U.S. Treasury and securities issued or guaranteed by federal agencies or authorities and U. S. government-sponsored instrumentalities or enterprises. The Fund will invest in pass-through securities. Pass-through securities include mortgage-backed securities such as those issued by Government National Mortgage Association (GNMA), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC). GNMA is an agency of the U.S. government and its securities are backed by the full faith and credit of the U.S. government. FNMA and FHLMC are U.S. government sponsored enterprises and their securities are backed by their credit. The Fund may invest in securities that have not been registered for sale under the Securities Act of 1933 pursuant to Rule 144A (Rule 144A securities) which are determined to be liquid by the Adviser. The Fund may seek to hedge the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets. In selecting securities for the Fund, the Adviser seeks securities providing relatively high current income. In making purchase and sales decisions for the Fund, the Adviser considers its economic outlook and interest rate forecast, as well as its evaluation of a security’s credit quality, yield, maturity, liquidity and the security’s sector. The Adviser attempts to maintain an average effective duration for the portfolio of approximately 0 to 2 years. The Adviser’s duration target within this range is based on its interest rate forecast. Duration is a measure of total price sensitivity relative to changes in interest rates. Portfolios with shorter durations are typically less sensitive to changes in interest rates.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with all mutual funds investing in bonds, the price and yield of the Fund may change daily due to interest rate changes and other factors. You could lose money by investing in the Fund. The principal risks of investing in the Fund are as follows: Call Risk: Many bonds may be redeemed (“called”) at the option of the issuer before their stated maturity date. In general, an issuer will call its bonds if they can be refinanced by issuing new bonds which bear a lower interest rate. The Fund would then be forced to invest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income. Credit Risk: The issuers or guarantors of securities (including U.S. government agencies and instrumentalities issuing securities that are not guaranteed by the full faith and credit of the U.S. government) owned by the Fund may default on the payment of principal or interest, or the other party to a contract may default on its obligations to the Fund, causing the value of the Fund to decrease. Income Risk: The income you earn from the Fund may decline due to declining interest rates. Interest Rate Risk: An increase in interest rates may lower the Fund’s value and the overall return on your investment. The magnitude of this decrease is often greater for longer-term fixed income securities than shorter-term securities. Liquidity Risk: The Fund may not be able to pay redemption proceeds within the time periods described in this Prospectus because of an inability to sell certain debt securities with more limited trading opportunities at a favorable price or time. Recent events have caused the markets for some debt securities to experience lower valuations and reduced liquidity. Consequently, the Fund may have to accept a lower price to sell a security, sell other securities to raise cash, or give up an investment opportunity, any of which could have a negative effect on the Fund’s performance. Infrequent trading may also lead to greater price volatility. Management Risk: A strategy used by the investment management team may not produce the intended results. Market Risk: The market value of securities may fall or fail to rise. Market risk may affect a single issuer, sector of the economy, industry, or the market as a whole. The market value of securities may fluctuate, sometimes rapidly and unpredictably. Mortgage and Asset-Backed Securities Risk: The value of these securities may be adversely affected by factors including changes in interest rates, the market value of the underlying assets, and the creditworthiness of the issuer or entities that provide credit enhancements. These securities are subject to prepayment risk and the impact of prepayments on the value of these securities may be difficult to predict and may result in greater volatility. Prepayment and Extension Risk: Declining interest rates may compel borrowers to prepay mortgages and debt obligations un- derlying the mortgage-backed securities owned by the Fund. The proceeds received by the Fund from prepayments will likely be reinvested at interest rates lower than the original investment, thus resulting in a reduction of income to the Fund. Likewise, rising interest rates could reduce prepayments and extend the life of securities with lower interest rates, which may increase the sensitivity of the Fund’s value to rising interest rates. Reinvestment Risk: Income from the Fund’s debt securities portfolio will decline if and when the Fund invests the proceeds from matured, traded or called securities in securities with market interest rates that are below the current earnings rate of the Fund’s portfolio. Rule 144A Securities Risk: The value and liquidity of these securities may be adversely affected in the event that the number of qualified institutional buyers interested in purchasing 144A securities is limited, the Fund might be unable to dispose of such securities promptly or at reasonable prices, and they may be subject to greater volatility. U.S. Government Securities Risk: Securities purchased by the Fund issued by Fannie Mae and Freddie Mac are neither issued nor guaranteed by the U.S. Treasury and, therefore, are not backed by the full faith and credit of the United States. There is a risk that the U.S. government will not provide financial support to U.S. government agencies or instrumentalities if it is not obligated to do so by law. Valuation Risk: The Fund may hold securities for which prices from pricing services may be unavailable or are deemed un- reliable, in which case the Fund’s procedures for valuing investments provide that the Adviser shall use the fair value of such securities for valuing investments. There is a risk that the fair value determined by the Adviser or the price determined by the pricing service may be different than the actual sale prices of such securities.
Risk Lose Money [Text]	rr_RiskLoseMoney	You could lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	HISTORICAL PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The Fund’s inception was December 31, 2012 and therefore there is no performance information to report at this time. For current performance information, call 1-800-332-5580 or visit www.sitfunds.com. The Fund’s past performance does not necessarily indicate how it will perform in the future.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	The Fund’s inception was December 31, 2012 and therefore there is no performance information to report at this time.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-332-5580
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.sitfunds.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance does not necessarily indicate how it will perform in the future.
Sit Quality Income Fund | Sit Quality Income Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_MaximumAccountFee	none
Management Fees	rr_ManagementFeesOverAssets	0.90%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.90%
1-Year	rr_ExpenseExampleYear01	92
3-Years	rr_ExpenseExampleYear03	288

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	SIT MUTUAL FUNDS II INC
Prospectus Date	rr_ProspectusDate	Dec. 31, 2012
Document Creation Date	dei_DocumentCreationDate	Dec. 17, 2012

XML

Document and Entity Information	12 Months Ended
	Dec. 31, 2012
Risk/Return:
Document Type	485BPOS
Document Period End Date	Dec. 17, 2012
Registrant Name	SIT MUTUAL FUNDS II INC
Central Index Key	0000746601
Amendment Flag	false
Document Creation Date	Dec. 17, 2012
Document Effective Date	Dec. 31, 2012
Prospectus Date	Dec. 31, 2012