Prospectus Certification by Investment Company (Form 497J)

May 1, 2026

VIA ELECTRONIC FILING

Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549

Attention: Division of Investment Management

RE: iShares Russell 2000 Small-Cap Index Fund and iShares MSCI EAFE

International Index Fund, each a series of BlackRock Index Funds, Inc.

Post-Effective Amendment No. 54 to the Registration Statement on Form N-1A

(Securities Act File No. 333-15265, Investment Company Act File No. 811-07899)

Ladies and Gentlemen:

Pursuant to Rule 497(j) under the Securities Act of 1933, as amended (the "1933 Act"), BlackRock Index Funds, Inc. (the "Registrant"), on behalf of its series iShares Russell 2000 Small-Cap Index Fund and iShares MSCI EAFE International Index Fund (together, the "Funds"), hereby certifies that:

(1) the form of Prospectuses and Statement of Additional Information that would have been filed pursuant to Rule 497(c) under the 1933 Act would not have differed from that contained in Post Effective Amendment No. 54 to the Registration Statement on Form N-1A of the Registrant with respect to the Funds; and

(2) the text of Post-Effective Amendment No. 54 to the Registration Statement on Form N-1A of the Registrant with respect to the Funds was filed electronically with the Securities and Exchange Commission on April 24, 2026.