OPPENHEIMER ROCHESTER® SHORT TERM MUNICIPAL FUND

Supplement dated July 26, 2013 to the

Prospectus and Statement of Additional Information, both dated September 28, 2012

This supplement amends the Prospectus and Statement of Additional Information (“SAI”) of Oppenheimer Rochester Short Term Municipal Fund (the “Fund”), both dated September 28, 2012, and is in addition to any other supplement.

Effective July 29, 2013 the Prospectus is revised as follows:

1. The section titled “Portfolio Managers” on page 6 of the Prospectus is deleted in its entirety and replaced with:

Daniel G. Loughran, CFA, Scott S. Cottier, CFA, Troy E. Willis, CFA, Mark R. DeMitry, CFA, and Michael L. Camarella, CFA, have each been a portfolio manager and Vice President of the Fund since its inception. Charles S. Pulire, CFA, has been a portfolio manager of the Fund since inception and a Vice President of the Fund since September 2011.Elizabeth S. Mossow, CFA, has been an associate portfolio manager of the Fund since July 2013.

2. The section titled “Ratings of Municipal Securities the Fund Buys” beginning on page 7 of the Prospectus is deleted and replaced in its entirety with:

Ratings of Municipal Securities the Fund Buys. The Sub-Adviser may rely to some extent on credit ratings by nationally recognized statistical rating organizations in evaluating the credit risk of securities selected for the Fund's portfolio. Credit ratings evaluate the expectation that scheduled interest and principal payments will be made in a timely manner. They do not reflect any judgment of market risk. Ratings and market value may change from time to time, positively or negatively, to reflect new developments regarding the issuer.

Rating organizations might not change their credit rating of an issuer in a timely manner to reflect events that could affect the issuer's ability to make timely payments on its obligations. In selecting securities for its portfolio and evaluating their income potential and credit risk, the Fund does not rely solely on ratings by rating organizations but evaluates business, economic and other factors affecting issuers as well. Many factors affect an issuer's ability to make timely payments, and the credit risk of a particular security may change over time. The Sub-Adviser also may use its own research and analysis to assess those risks. If a bond is insured, it will usually be rated by the rating organizations based on the financial strength of the insurer. The rating categories are described in an Appendix to the Statement of Additional Information.

Most of the municipal securities the Fund buys are "investment-grade" at the time of purchase. "Investment-grade" securities are those rated within the four highest rating categories of Standard & Poor's, Moody's, Fitch or another nationally recognized statistical rating organization (or, in the case of unrated securities, determined by Sub-Adviser to be comparable to securities rated investment-grade). While securities rated within the fourth highest category by Standard & Poor's (meaning BBB+, BBB or BBB-) or by Moody's (meaning Baa1, Baa2 or Baa3) are considered "investment-grade," they have some speculative characteristics. If two or more nationally recognized statistical rating organizations have assigned different ratings to a security, the Sub-Adviser uses the highest rating assigned.

The Fund will not invest more than 15% of its total assets in securities rated below the top three rating categories or unrated securities that are assigned similar ratings.

3. The section titled “Special Risks of Lower-Grade Securities” on page 8 of the Prospectus is deleted in its entirety and replaced with:

Risks of Below-Investment-Grade Securities. Below-investment-grade securities (also referred to as “junk bonds”) generally have higher yields than securities rated in the higher rating categories but also have higher risk profiles. Below-investment-grade securities are considered to be speculative and entail greater risk with respect to the ability of the issuer to timely repay principal and pay interest or dividends in accordance with the terms of the obligation and may have more credit risk than investment-grade rated securities. These additional risks mean that the Fund may not receive the anticipated level of income from these securities, and the Fund’s net asset value may be affected by declines in the value of lower-grade securities. The major risks of below-investment-grade securities include:

· Prices of below-investment-grade securities are subject to extreme price fluctuations, even under normal market conditions. Adverse changes in an issuer’s industry and general economic conditions may have a greater impact on the prices of below-investment-grade securities than on the prices of higher-rated fixed-income securities.

· Below-investment-grade securities may be issued by less creditworthy issuers and may be more likely to default than investment-grade securities. Issuers of below-investment-grade securities may have more outstanding debt relative to their assets than issuers of higher-grade securities. Issuers of below-investment-grade securities may be unable to meet their interest or principal payment obligations because of an economic downturn, specific issuer developments, or the unavailability of additional financing.

· In the event of an issuer’s bankruptcy, claims of other creditors may have priority over the claims of below-investment-grade securities holders.

· Below-investment-grade securities may be less liquid than higher rated fixed-income securities, even under normal market conditions. There are fewer dealers in the below-investment-grade securities market and there may be significant differences in the prices quoted by the dealers. Because they are less liquid, judgment may play a greater role in valuing certain of the Fund’s securities than is the case with securities trading in a more liquid market.

· Below-investment-grade securities typically contain redemption provisions that permit the issuer of the securities containing such provisions to redeem the securities at its discretion. If the issuer redeems below-investment-grade securities, the Fund may have to invest the proceeds in securities with lower yields and may lose income.

· Below-investment-grade securities markets may be more susceptible to real or perceived adverse credit, economic, or market conditions than higher rated securities.

The Fund can invest up to 5% of its total assets in below-investment-grade securities. This restriction is applied at the time of purchase and the Fund may continue to hold a security whose credit rating has been downgraded or, in the case of an unrated security, after the Fund's Sub-Adviser has changed its assessment of the security's credit quality. As a result, credit rating downgrades or other market fluctuations may cause the Fund's holdings of below-investment-grade securities to exceed, at times significantly, this restriction for an extended period of time. Credit rating downgrades of a single issuer or related similar issuers whose securities the Fund holds in significant amounts could substantially and unexpectedly increase the Fund’s exposure to below-investment-grade securities and the risks associated with them, especially liquidity and default risk. If the Fund has more than 5% of its total assets invested in below-investment-grade securities, the Sub-Adviser will not purchase additional below-investment-grade securities until the level of holdings in those securities no longer exceeds the restriction.

4. The first paragraph of the section titled “Portfolio Managers” on page 10 of the Prospectus is deleted and replaced in its entirety with:

The Fund’s portfolio is managed by a team of investment professionals, including Daniel G. Loughran, CFA, Scott S. Cottier, CFA, Troy E. Willis, J.D., CFA, Mark R. DeMitry, CFA, Michael L. Camarella, CFA, Charles S. Pulire, CFA, and Elizabeth S. Mossow, CFA, who are primarily responsible for the day-to-day management of the Fund’s investments. Mr. Loughran, Mr. Cottier, Mr. Willis, Mr. DeMitry, and Mr. Camarella have each been a portfolio manager and Vice President of the Fund since its inception. Mr. Pulire has been a portfolio manager of the Fund since inception and a Vice President of the Fund since September 2011. Mrs. Mossow has been an associate portfolio manager of the Fund since July 2013.

5. The following is added to the section titled “Portfolio Managers” on page 10 of the Prospectus:

Mrs. Mossow has been an Assistant Vice President of the Sub-Adviser since January 2011 and an Associate Portfolio Manager of the Sub-Adviser since June 2013. She was a Portfolio Research Analyst of the Sub-Adviser from June 2011 to June 2013 and was a Credit Analyst of the Sub-Adviser from May 2007 to May 2011. She was a Risk Management Analyst at Manning & Napier Associates from September 2006 to May 2007 and was an Analyst/Trading Assistant at The Baupost Group from August 2000 to March 2006. Mrs. Mossow is a portfolio manager and a trader for the Fund and other Oppenheimer funds.

Effective July 29, 2013, the SAI is revised as follows:

1. The section titled “Credit Ratings of Municipal Securities” beginning on page 6 of the SAI is deleted in its entirety and replaced with:

Credit Ratings of Municipal Securities. Ratings by ratings organizations such as Moody's Investors Service, Inc. ("Moody's"), Standard & Poor's Ratings Services ("S&P"), and Fitch, Inc. ("Fitch") represent the respective rating agency's opinions of the credit quality of the municipal securities they undertake to rate. However, their ratings are general opinions and are not guarantees of quality or indicative of market value risk. Municipal securities that have the same maturity, coupon and rating may have different yields, while other municipal securities that have the same maturity and coupon but different ratings may have the same yield. Ratings and market value may change from time to time, positively or negatively, to reflect new developments regarding the issuer.

"Investment-grade" securities are those rated within the four highest rating categories of S&P's, Moody's, Fitch or another nationally recognized statistical rating organization (or, in the case of unrated securities, determined by the Sub-Adviser to be comparable to securities rated investment-grade). While securities rated within the fourth highest category by S&P's (meaning BBB+, BBB or BBB-) or by Moody's (meaning Baa1, Baa2 or Baa3) are considered "investment-grade," they have some speculative characteristics. If two or more nationally recognized statistical rating organizations have assigned different ratings to a security, the Sub-Adviser uses the highest rating assigned.

Below-investment-grade securities (also referred to as "junk bonds") are those rated below investment grade by the S&P, Moody’s, Fitch or other nationally recognized statistical rating organization or unrated securities the Sub-Adviser believes are of comparable quality.

After the Fund buys a municipal security, the security may cease to be rated or its rating may be reduced. Neither event requires the Fund to sell the security, but the Sub-Adviser will consider such events in determining whether the Fund should continue to hold the security. To the extent that ratings given by Moody's, S&P, Fitch or another nationally recognized statistical rating organization change as a result of changes in those rating organizations or their rating systems, the Fund will attempt to use similar ratings as standards for investments in accordance with the Fund's investment policies. The Sub-Adviser continuously monitors the issuers of below-investment-grade securities held by the Fund for their ability to make required principal and interest payments, as well as in an effort to control the liquidity of the Fund so that it can meet redemption requests.

The Fund may buy municipal securities that are "pre-refunded." The issuer's obligation to repay the principal value of the security is generally collateralized with U.S. government securities placed in an escrow account. This causes the pre-refunded security to have essentially the same risks of default as a AAA-rated security.

A list of the rating categories of Moody's, S&P, Fitch and other nationally recognized statistical rating organizations for municipal securities is contained in an Appendix to this SAI.

2. The section titled “Special Risks of Below-Investment-Grade Securities” on page 7 of the SAI is deleted in its entirety and replaced with:

Special Risks of Below-Investment-Grade Securities. While below-investment-grade securities generally may have a higher yield than securities rated in the higher rating categories, they are subject to increased risks. Below-investment-grade securities are considered to be speculative with respect to the ability of the issuer to timely repay principal and pay interest or dividends in accordance with the terms of the obligation and may have more credit risk than investment-grade rated securities. The major risks of below-investment-grade securities include:

· Prices of below-investment-grade securities are subject to extreme price fluctuations, even under normal market conditions. Negative economic developments may have a greater impact on the prices of below-investment-grade securities than on those of other higher-rated fixed income securities. In addition, the market values of below-investment-grade securities tend to reflect individual issuer developments to a greater extent than do the market values of higher rated securities, which react primarily to fluctuations in the general level of interest rates.

· Below-investment-grade securities may be issued by less creditworthy issuers and may be more likely to default than investment-grade securities. The issuers of below-investment-grade securities may have more outstanding debt relative to their assets than issuers of higher-grade securities. Below-investment-grade securities are vulnerable to adverse changes in the issuer’s industry and to general economic conditions. If the issuers experiences financial stress, it may not be able to pay interest and principal payments in a timely manner. The issuer’s ability to pay its debt obligations also may be lessened by specific issuer developments or the unavailability of additional financing. In the event of a default of an issuer of a below-investment-grade security, the Fund may incur expenses to the extent necessary to seek recovery or to negotiate new terms.

· Below-investment-grade securities are frequently ranked junior to claims by other creditors. If the issuer cannot meet its obligations, the senior obligations are generally paid off before the junior obligations, which could limit the Fund’s ability to fully recover principal or to receive interest payments when senior securities are in default. As a result, investors in below-investment-grade securities have a lower degree of protection with respect to principal and interest payments than do investors in higher rated securities.

· There may be less of a market for below-investment securities and as a result they may be harder to sell at an acceptable price. Not all dealers maintain markets in all below-investment-grade securities. As a result, there is no established retail secondary market for many of these securities. The Fund anticipates that such securities could be sold only to a limited number of dealers or institutional investors. To the extent a secondary trading market does exist, it is generally not as liquid as the secondary market for higher rated securities. The lack of a liquid secondary market may have an adverse impact on the market price of the security. The lack of a liquid secondary market for certain securities may also make it more difficult for the Fund to obtain accurate market quotations for purposes of valuing its securities. Market quotations are generally available on many below-investment-grade securities only from a limited number of dealers and may not necessarily represent firm bids of such dealers or prices for actual sales. In addition, the trading volume for below-investment-grade securities is generally lower than that for higher rated securities and the secondary markets could contract under adverse market or economic conditions independent of any specific adverse changes in the condition of a particular issuer. Under certain economic and/or market conditions, the Fund may have difficulty disposing of certain below-investment-grade securities due to the limit number of investors in that sector of the market. When the secondary market for below-investment-grade securities becomes more illiquid, or in the absence of readily available market quotations for such securities, the relative lack of reliable objective data makes it more difficult to value the Fund’s securities and judgment plays a more important role in determining such valuations.

· Below-investment-grade securities frequently have redemption features that permit an issuer to repurchase the security from the Fund before it matures. During times of falling interest rates, issuers of these securities are likely to redeem or prepay the securities and finance them with securities with a lower interest rate. To the extent an issuer is able to refinance the securities, or otherwise redeem them; the Fund may have to replace the securities with lower yielding securities, which could result in a lower return for the Fund.

· Below-investment-grade securities markets may also react strongly to adverse news about an issuer or the economy, or to the perception or expectation of adverse news, whether or not it is based on fundamental analysis. An increase in interest rates could severely disrupt the market for below-investment-grade securities. Additionally, below-investment-grade securities may be affected by legislative and regulatory developments. These developments could adversely affect a Fund’s net asset value and investment practices, the secondary market for below-investment-grade securities, the financial condition of issuers of these securities and the value and liquidity of outstanding below-investment-grade securities, especially in a thinly traded market.

These additional risks mean that the Fund may not receive the anticipated level of income from these securities, and the Fund's net asset value may be affected by declines in the value of lower-grade securities. Credit rating downgrades of a single issuer or related similar issuers whose securities the Fund holds in significant amounts could substantially and unexpectedly increase the Fund’s exposure to below-investment-grade securities and the risks associated with them, especially liquidity and default risk.

While securities rated "Baa" by Moody's, "BBB" by S&P, or the similar category by the Sub-Adviser if an unrated security, are investment-grade, they may be subject to special risks and have some speculative characteristics.

3. The sections titled “Portfolio Managers” and “Other Accounts Managed” on page 40 of the SAI are revised to reflect the addition of Elizabeth Mossow as a Portfolio Manager.

4. Other Accounts Managed. The following table provides information regarding the other portfolios and accounts managed by Mrs. Mossow as of July 15, 2013.

Portfolio Manager	Registered Investment Companies Managed	Total Assets in Registered Investment Companies Managed	Other Pooled Investment Vehicles	Total Assets in Other Pooled Investment Vehicles	Other Accounts Managed	Total Assets in Other Accounts Managed1
Elizabeth S. Mossow2	n/a	n/a	n/a	n/a	n/a	n/a

¹ Does not include personal accounts of the portfolio manager and her family, which are subject to the Code of Ethics.

² Mrs. Mossow did not become a portfolio manager until July 29, 2013.

5. Ownership of Fund Shares. The following information, as of July 15, 2013, is added to the “Ownership of Fund Shares” table on page 41 of the SAI:

      Portfolio Manager                                  Range of Shares Beneficially Owned in the Fund

Elizabeth S. Mossow None

July 26, 2013                                                                                                                      PS0621.002