As filed with the Securities and Exchange Commission on October 15, 2014

Securities Act File No. 333-56203

Investment Company Act File No. 811-08797

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. 36	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 80	x

(Check appropriate box or boxes)

BLACKROCK SMALL CAP GROWTH FUND II

OF BLACKROCK SERIES, INC.

(Exact Name of Registrant as Specified in Charter)

100 Bellevue Parkway

Wilmington, Delaware 19809

(Address of Principal Executive Office)

Registrant’s Telephone Number, including Area Code (800) 441-7762

John M. Perlowski

BlackRock Small Cap Growth Fund II

of BlackRock Series, Inc.

55 East 52^nd Street

New York, New York 10055

United States of America

(Name and Address of Agent for Service)

Copies to:

John A. MacKinnon, Esq. Sidley Austin LLP 787 Seventh Avenue New York, New York 10019-6018 Benjamin Archibald, Esq. BlackRock Advisors, LLC 55 East 52^nd Street New York, New York 10055

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

x Immediately upon filing pursuant to paragraph (b)

¨ On (date) pursuant to paragraph (b)

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

¨ On (date) pursuant to paragraph (a)(1)

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

¨ On (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.

Title of Securities Being Registered: Shares of common stock, par value $.0001 per share.

BlackRock Master LLC has also executed this Registration Statement.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this Post-Effective Amendment to its Registration Statement pursuant to
Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment to its Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York and the State of New York, on October 15, 2014.

BLACKROCK SMALL CAP GROWTH FUND II OF BLACKROCK SERIES, INC.
By	/s/    JOHN M. PERLOWSKI
	John M. Perlowski President and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to its Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/    JOHN M. PERLOWSKI         John M. Perlowski	President and Chief Executive Officer (Principal Executive Officer)	October 15, 2014
/s/    NEAL J. ANDREWS         Neal J. Andrews	Chief Financial Officer (Principal Financial and Accounting Officer)	October 15, 2014
DAVID O. BEIM* David O. Beim	Director
FRANK J. FABOZZI* Frank J. Fabozzi	Director
RONALD W. FORBES* Ronald W. Forbes	Director
DR. MATINA S. HORNER* Dr. Matina S. Horner	Director
RODNEY D. JOHNSON* Rodney D. Johnson	Director
HERBERT I. LONDON* Herbert I. London	Director
IAN A. MACKINNON* Ian A. MacKinnon	Director
CYNTHIA A. MONTGOMERY* Cynthia A. Montgomery	Director
JOSEPH P. PLATT* Joseph P. Platt	Director
ROBERT C. ROBB, JR.* Robert C. Robb, Jr.	Director
TOBY ROSENBLATT* Toby Rosenblatt	Director

2

KENNETH L. URISH* Kenneth L. Urish	Director
FREDERICK W. WINTER* Frederick W. Winter	Director
Paul L. Audet* Paul L. Audet	Director
HENRY GABBAY* Henry Gabbay	Director

*By:	/s/     BENJAMIN ARCHIBALD	October 15, 2014
	Benjamin Archibald (Attorney-in-Fact)

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SIGNATURES

BlackRock Master LLC has duly caused this Post-Effective Amendment to the Registration Statement of BlackRock Small Cap Growth Fund II of BlackRock Series, Inc. to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York and the State of New York, on October 15, 2014.

BLACKROCK MASTER SMALL CAP GROWTH     PORTFOLIO OF BLACKROCK MASTER LLC
By	/s/    JOHN M. PERLOWSKI
	John M. Perlowski
	President and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to the Registration Statement of BlackRock Small Cap Growth Fund II of BlackRock Series, Inc. has been signed below by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/    JOHN M. PERLOWSKI	President and Chief Executive Officer	October 15, 2014
John M. Perlowski	(Principal Executive Officer)
/s/    NEAL J. ANDREWS	Chief Financial Officer (Principal	October 15, 2014
Neal J. Andrews	Financial and Accounting Officer)
DAVID O. BEIM*	Director
David O. Beim
FRANK J. FABOZZI*	Director
Frank J. Fabozzi
RONALD W. FORBES*	Director
Ronald W. Forbes
DR. MATINA S. HORNER*	Director
Dr. Matina S. Horner
RODNEY D. JOHNSON*	Director
Rodney D. Johnson
HERBERT I. LONDON*	Director
Herbert I. London
IAN A. MACKINNON*	Director
Ian A. MacKinnon
CYNTHIA A. MONTGOMERY*	Director
Cynthia A. Montgomery
JOSEPH P. PLATT*	Director
Joseph P. Platt
ROBERT C. ROBB, JR.*	Director
Robert C. Robb, Jr.
TOBY ROSENBLATT*	Director
Toby Rosenblatt
KENNETH L. URISH* Kenneth L. Urish	Director

4

FREDERICK W. WINTER* Frederick W. Winter	Director
Paul L. Audet* Paul L. Audet	Director
HENRY GABBAY* Henry Gabbay	Director

*By:	/s/    BENJAMIN ARCHIBALD	October 15, 2014
	Benjamin Archibald (Attorney-in-Fact)

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EXHIBIT INDEX

Index No.	Description of Exhibit
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.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

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