<Page> [ANNOTATED FORM N-CSR FOR ANNUAL REPORTS] UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM N-CSR CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES Investment Company Act file number: 811-05624 ------------------------------------------------- Morgan Stanley Institutional Fund, Inc. - -------------------------------------------------------------------------------- (Exact name of registrant as specified in charter) 1221 Avenue of the America's 22nd Floor New York, NY 10020 - -------------------------------------------------------------------------------- (Address of principal executive offices) (Zip code) Ronald E. Robison 1221 Avenue of the Americas, 33rd Floor New York, New York 10020 - -------------------------------------------------------------------------------- (Name and address of agent for service) Registrant's telephone number, including area code: 1-800-221-6726 ----------------------------------- Date of fiscal year end: 12/31 -------------------------------------------------------------- Date of reporting period: 12/31/04 -------------------------------------------------------------- Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles. A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget ("OMB") control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. Section 3507. <Page> ITEMS 1-12. The Fund's annual report transmitted to shareholders pursuant to Rule 30e-1 under the Investment Company Act of 1940 and filed under ITEM 1 of Form N-CSR on March 9, 2005 and amended under ITEM 1 of Form N-CSR/A on April 22, 2005 is hereby incorporated by reference. Responses to ITEMS 2-12 in the above mentioned filings, including related attachments and exhibits are also hereby incorporated by reference, with the exception of the certifications of the principal executive officer and principal financial officer which are attached hereto as part of EX-99.CERT. <Page> SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. (Registrant) Morgan Stanley Institutional Fund, Inc. -------------------------------------------------------------------- By: /s/ Ronald E. Robison ----------------------------------------------------------------------------- Name: Ronald E. Robison Title: Principal Executive Officer Date: 6/22/2005 Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed by the following persons on behalf of the registrant and in the capacities and on the dates indicated. By: /s/ Ronald E. Robison ----------------------------------------------------------------------------- Name: Ronald E. Robison Title: Principal Executive Officer Date: 6/22/2005 By: /s/ James W. Garrett ----------------------------------------------------------------------------- Name: James W. Garrett Title: Chief Financial Officer Date: 6/22/2005