Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus and other information about the Fund, including the Statement of Additional Information (“SAI”) and most recent reports to shareholders, online at http://hosted.rightprospectus.com/Jackson/JNLSeriesTrust. You can also get this information at no cost by calling 1-800-644-4565 (Annuity and Life Service Center), 1-800-599-5651 (NY Annuity and Life Service Center), 1-800-777-7779 (for contracts purchased through a bank or financial institution) or 1-888-464-7779 (for NY contracts purchased through a bank or financial institution), or by sending an email request to ProspectusRequest@jackson.com. The current Prospectus and SAI, both dated April 29, 2019, are incorporated by reference into (which means they legally are a part of) this Summary Prospectus.

Beginning on January 1, 2021, as permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Funds’ annual and semi annual shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the reports from Jackson. Instead, the reports will be made available on Jackson’s website (www.jackson.com), and you will be notified by mail each time a report is posted and provided with a website link to access the report.

If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from Jackson electronically by doing one of the following:

Beginning on January 1, 2019, you may elect to receive all future reports in paper free of charge. You can inform Jackson that you wish to continue receiving paper copies of your shareholder reports by contacting the appropriate Jackson Service Center. Your election to receive reports in paper will apply to all Funds held in each variable contract you purchased from Jackson.

The expenses do not reflect the expenses of the variable insurance contracts or the separate account through which you indirectly invest in the Fund, whichever may be applicable, and the total expenses would be higher if they were included.

JNAM has contractually agreed to waive a portion of the Fund’s management fee in an amount equal to 100% of the net advisory fees payable to an affiliate of the sub-adviser attributable to the Fund’s investment in funds managed by that affiliate. The waiver will have the effect of reducing the Acquired Fund Fees and Expenses that are indirectly borne by the Fund. The waiver will continue for at least one year from the date of this Prospectus, so long as the sub-advisory agreement remains in effect, unless the Board of Trustees approves a change in or elimination of the waiver. The impact of this waiver was less than 0.01% for the previous fiscal year.

Expense 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. Also, this example does not reflect the expenses of the variable insurance contracts or the separate account through which you indirectly invest in the Fund, whichever may be applicable, and the total expenses would be higher if they were included. The table below shows the expenses you would pay on a $10,000 investment, assuming (1) 5% annual return; (2) redemption at the end of each time period; and (3) that the Fund operating expenses remain the same. The example also assumes that the contractual expense limitation agreement is not renewed. The example does not reflect the voluntary fee waiver. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover (% of average value of portfolio). The Fund pays transaction 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. These costs, which are not reflected in Annual Fund Operating Expenses or in the Expense Example above, affect the Fund’s performance.

Principal Investment Strategies. The Fund seeks to achieve its objective by investing at least 80% of its assets (net assets plus the amount of any borrowings made for investment purposes), under normal circumstances, in a broadly diversified portfolio of common stocks of medium-sized (mid-capitalization) companies whose earnings T. Rowe Price Associates, Inc., one of the Fund’s sub-advisers (each, a “Sub-Adviser”) expects to grow at a faster rate than the average company.

T. Rowe Price Associates, Inc. defines mid-capitalization companies as those whose market capitalization, at the time of acquisition by the Fund, falls within the capitalization range of companies in the S&P Mid Cap 400 Index or the Russell MidCap^® Growth Index. The market capitalization of companies in the Fund’s portfolio, the S&P Mid Cap 400 Index and the Russell MidCap^® Growth Index changes over time. As of December 31, 2018, the market capitalization range for the S&P Mid Cap 400 is $1.1 billion to $22.7 billion. As of December 31, 2018, the market capitalization range for the Russell MidCap Growth is $1.6 billion to $35.6 billion. However, the Fund will not automatically sell or cease to purchase stock of a company it already owns just because the company’s market capitalization subsequently grows or otherwise falls outside these ranges.

Depending upon cash flows into and out of the Fund, the Adviser may direct up to 20% of the portfolio be invested in a mid-capitalization growth index strategy (“index sleeve”) managed by Mellon Investments Corporation ("Mellon"). For the index sleeve, the Fund employs a passive investment approach, called indexing. For the index sleeve, the Fund does not employ traditional methods of active investment management, which involves the buying and selling of securities based upon individual security analysis. The index sleeve attempts to replicate the Russell MidCap^® Growth Index by investing all or substantially all of its assets in the stocks that make up the Russell MidCap^® Growth Index in proportion to their market capitalization weighting in the Russell MidCap^® Growth Index. The index sleeve managed by Mellon attempts to replicate the Russell MidCap Growth Index by replicating a majority of the Russell MidCap Growth Index and sampling from the securities remaining in the index.

In addition, the Fund on occasion will purchase stock of some larger and smaller companies that have qualities consistent with the portfolio’s core characteristics but whose market capitalization is outside the capitalization range of mid-cap companies (as defined above) at the time of purchase. The Fund may also invest up to 25% of its total assets, (excluding reserves) in foreign securities, including securities and instruments that are economically tied to emerging markets, and 10% of its assets in futures.

Principal Risks of Investing in the Fund. An investment in the Fund is not guaranteed. As with any mutual fund, the value of the Fund’s shares will change, and you could lose money by investing in the Fund. The principal risks associated with investing in the Fund include:

Managed portfolio risk – As an actively managed portfolio, the value of the Fund’s investments could decline because the financial condition of an issuer may change (due to such factors as management performance, reduced demand or overall market changes), financial markets may fluctuate or overall prices may decline, or the Sub-Adviser's investment techniques could fail to achieve the Fund’s investment objective or negatively affect the Fund’s investment performance.

Stock risk – Stock markets may experience significant short-term volatility and may fall sharply at times. Different stock markets may behave differently from each other and U.S. stock markets may move in the opposite direction from one or more foreign stock markets. The prices of individual stocks generally do not all move in the same direction at the same time and a variety of factors can affect the price of a particular company’s stock.

Investment style risk – The returns from a certain investment style may be lower than the returns from the overall stock market. Value stocks may not increase in price if other investors fail to recognize the company’s value or the factors that are expected to increase the price of the security do not occur. Growth stock prices frequently reflect projections of future earnings or revenues, and if earnings growth expectations are not met, their stock prices will likely fall, which may reduce the value of a Fund’s investment in those stocks. Over market cycles, different investment styles may sometimes outperform other investment styles (for example, growth investing may outperform value investing).

Investment strategy risk – The investment manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. Investment decisions made by the investment manager in accordance with these investment strategies may not produce the returns the investment manager expected, and may cause the Fund’s shares to decline in value or may cause the Fund to underperform other funds with similar investment objectives.

Foreign securities risk – Investments in, or exposure to, foreign securities involve risks not typically associated with U.S. investments. These risks include, among others, adverse fluctuations in foreign currency values, possible imposition of foreign withholding or other taxes on income payable on the securities, as well as adverse political, social and economic developments, such as political upheaval, acts of terrorism, financial troubles, or natural disasters. Many foreign securities markets, especially those in emerging market countries, are less stable, smaller, less liquid, and less regulated than U.S. securities markets, and the costs of trading in those markets is often higher than in U.S. securities markets. There may also be less publicly available information about issuers of foreign securities compared to issuers of U.S. securities. In addition, the economies of certain foreign markets may not compare favorably with the economy of the United States with respect to issues such as growth of gross national product, reinvestment of capital, resources and balance of payments position.

Foreign regulatory risk – The Adviser is an indirect wholly owned subsidiary of Prudential plc, a publicly traded company incorporated in the United Kingdom and is not affiliated in any manner with Prudential Financial Inc., a company whose principal place of business is in the United States of America. Through its ownership structure, the Adviser has a number of global financial industry affiliates. As a result of this structure, and the asset management and financial industry business activities of the Adviser and its affiliates, the Adviser and the Fund may be prohibited or limited in effecting transactions in certain securities. Additionally, the Adviser and the Fund may encounter trading limitations or restrictions because of aggregation issues or other foreign regulatory requirements. Foreign regulators or foreign laws may impose position limits on securities held by the Fund, and the Fund may be limited as to which securities it may purchase or sell, as well as the timing of such purchases or sales. These foreign regulatory limits may increase the Fund’s expenses and may limit the Fund’s performance.

Sector risk – Companies with similar characteristics may be grouped together in broad categories called sectors. Sector risk is the risk that securities of companies within specific sectors of the economy can perform differently than the overall market. For example, this may be due to changes in the regulatory or competitive environment or changes in investor perceptions regarding a sector. Because the Fund may allocate relatively more assets to certain sectors than others, the Fund’s performance may be more susceptible to any developments which affect those sectors emphasized by the Fund. In addition, the Fund could underperform other funds investing in similar sectors or comparable benchmarks because of the investment manager’s choice of securities within such sector.

Market risk – Portfolio securities may decline in value due to factors affecting securities markets generally, such as real or perceived adverse economic, political, or regulatory conditions, inflation, changes in interest or currency rates or adverse investor sentiment, among others. Adverse market conditions may be prolonged and may not have the same impact on all types of securities. The values of securities may fall due to factors affecting a particular issuer, industry or the securities market as a whole.

Equity securities risk – Common and preferred stocks represent equity ownership in a company. Stock markets are volatile, and equity securities generally have greater price volatility than fixed-income securities. The price of equity or equity-related securities will fluctuate and can decline and reduce the value of a portfolio investing in equity or equity-related securities. The value of equity or equity-related securities purchased by the Fund could decline if the financial condition of the companies the Fund invests in decline or if overall market and economic conditions deteriorate. They may also decline due to factors that affect a particular industry or industries, such as labor shortages or an increase in production costs and competitive conditions within an industry. In addition, they may decline due to general market conditions that are not specifically related to a company or industry, such as real or perceived adverse economic conditions, changes in the general outlook for corporate earnings, changes in interest or currency rates or generally adverse investor sentiment.

Index investing risk – The Fund’s indexing strategy does not attempt to manage volatility, use defensive strategies, or reduce the effects of any long-term periods of poor stock performance. Should a Fund engage in index sampling, the performance of the securities selected will not provide investment performance matching that of the Index. Fund performance may not exactly correspond with the performance of the relevant index for a number of reasons, including, but not limited to: the timing of purchases and redemptions of the Fund’s shares, changes in the composition of the index, and the Fund’s expenses. Certain regulatory limitations, such as Fund diversification requirements, may limit the ability of a Fund to completely replicate an index.

Financial services risk – An investment in issuers in the financial services sector may be adversely affected by, among other things: (i) changes in the regulatory framework or interest rates that may negatively affect financial service businesses; (ii) exposure of a financial institution to a non-diversified or concentrated loan portfolio; (iii) exposure to financial leverage and/or investments or agreements which, under certain circumstances, may lead to losses (e.g., sub-prime loans); and (iv) the risk that a market shock or other unexpected market, economic, political, regulatory, or other event might lead to a sudden decline in the values of most or all companies in the financial services sector.

Accounting risk – The Fund bases investment selections, in part, on information drawn from the financial statements of issuers. Financial statements may not be accurate, may reflect differing approaches with respect to auditing and reporting standards and may affect the ability of the Fund’s investment manager to identify appropriate investment opportunities.

Performance. The performance information shown provides some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns compared with those of broad-based securities market indices which have investment characteristics similar to those of the Fund. The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Only separate accounts of Jackson National Life Insurance Company (“Jackson”) or Jackson National Life Insurance Company of New York (“Jackson NY”) and series, including fund of funds, of registered investment companies in which either or both of those insurance companies invest may purchase shares of the Fund. You may invest indirectly in the Fund through your purchase of a variable annuity or life insurance contract issued by a separate account of Jackson or Jackson NY that invests directly, or through a fund of funds, in this Fund. Any minimum initial or subsequent investment requirements and redemption procedures are governed by the applicable separate account through which you invest indirectly.

The Fund expects to be treated as a partnership for U.S. federal income tax purposes, and does not expect to make regular distributions (other than in redemption of Fund shares) to shareholders, which generally are the participating insurance companies investing in the Fund through separate accounts of Jackson or Jackson NY and mutual funds owned directly or indirectly by such separate accounts. You should consult the prospectus of the appropriate separate account or description of the plan for a discussion of the U.S. federal income tax consequences to you of your contract, policy, or plan.

If you invest in the Fund under a variable insurance contract or a plan that offers a variable insurance contract as a plan option through a broker-dealer or other financial intermediary (such as a financial institution), the Fund and its related companies may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s Website for more information.

Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
	Class A
Management Fee	0.60%
Distribution and/or Service (12b-1) Fees	0.30%
Other Expenses¹	0.10%
Total Annual Fund Operating Expenses	1.00%

Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
	Class I
Management Fee	0.60%
Distribution and/or Service (12b-1) Fees	0.00%
Other Expenses¹	0.10%
Total Annual Fund Operating Expenses	0.70%

JNL/T. Rowe Price Mid-Cap Growth Fund Class A
1 year	3 years	5 years	10 years
$102	$318	$552	$1,225

JNL/T. Rowe Price Mid-Cap Growth Fund Class I
1 year	3 years	5 years	10 years
$72	$224	$390	$871

Average Annual Total Returns as of 12/31/2018
	1 year		5 year		10 year
JNL/T. Rowe Price Mid-Cap Growth Fund (Class A)	-2.45	%	9.12	%	16.08	%
MSCI USA Mid Cap Growth Index (Gross) (reflects no deduction for fees, expenses, or taxes)	-7.92	%	5.99	%	14.41	%

Name:	Joined Fund Management Team In:	Title:
Brian W.H. Berghuis, CFA	1995	Chairman of Investment Advisory Committee, T. Rowe Price
Karen Q. Wong, CFA	2011	Managing Director, Mellon
Richard A. Brown, CFA	2011	Managing Director, Mellon
Thomas J. Durante, CFA	2011	Managing Director, Mellon

Period
1/1/2018 - 12/31/2018	29	%