BlackRock Series, Inc.
BlackRock Small Cap Growth Fund II
(the “Fund”)

Supplement dated June 16, 2015 to the
Statement of Additional Information of the Fund

Effective June 1, 2015, Part II of the Fund’s Statement of Additional Information is amended as follows:

The last paragraph under the section entitled “Purchase of Shares — Other Compensation to Selling Dealers” in Part II of the Fund’s current Statement of Additional Information is deleted in its entirety and replaced with the following:

As of the date of this SAI, as amended or supplemented from time to time, the following Service Organizations are receiving such payments: Ameriprise Financial Services, AXA Advisors, CCO Investment Services, Cetera Financial Group, Citigroup Global Markets, Inc., Commonwealth Equity Services (Commonwealth Financial Network), FSC Securities Corporation, Investacorp, Inc., JP Morgan, LPL Financial Corporation, Merrill Lynch, MetLife Securities, Morgan Stanley Smith Barney, Northwestern Mutual Investment Services, LLC, Park Avenue Securities, PFS Investments, PNC Investments LLC, Raymond James, RBC Capital Markets, Royal Alliance Associates, SagePoint Financial, Santander Securities, LLC, Securities America, State Farm VP Management Corp., The Huntington Investment Co., Triad Advisors, Inc., UBS Financial Services, U.S. Bancorp Investments, Voya Financial Advisors, Inc., Voya Investments Distributor, LLC, Wells Fargo, Woodbury Financial Services, Inc. and/or broker dealers and other financial services firms under common control with the above organizations (or their successors or assignees). The level of payments made to these Service Organizations in any year will vary, may be limited to specific Funds or share classes, and normally will not exceed the sum of (a) 0.25% of such year’s Fund sales by that Service Organization and (b) 0.21% of the assets attributable to that Service Organization invested in a Fund. In certain cases, the payments described in the preceding sentence are subject to certain minimum payment levels. In addition, from time to time BRIL, BlackRock or certain of their affiliates may make fixed dollar amount payments to certain Service Organizations listed above that are not based on the value of the shares sold to, or held by, the Service Organization’s customers and may be different for different Service Organizations.

Shareholders should retain this Supplement for future reference.

SAI-19072-0615SUP