
<PAGE>   1

                       SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C.  20549


                                   FORM 8-K/A

                               AMENDMENT NO. 1 TO

                                 CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934


DATE OF REPORT (DATE OF EARLIEST EVENT REPORTED): MARCH 17, 1997


                         COMMISSION FILE NUMBER 0-27130


                            NETWORK APPLIANCE, INC.
               (EXACT NAME OF REGISTRANT AS SPECIFIED IN CHARTER)


             CALIFORNIA                                77-0307520
     (State or other jurisdiction                    (IRS Employer
         of incorporation)                       Identification No.)


2770 SAN TOMAS EXPRESSWAY, SANTA CLARA, CALIFORNIA       95051
   (Address of principal executive offices)           (Zip Code)

Company's telephone number, including area code:     (408) 367-3000


         319 BERNARDO AVE., MOUNTAIN VIEW, CA            94043
         Former name or former address, if changed since last report



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         This report amends the Registrant's report on Form 8-K, initially
filed on March 28, 1997, to provide financial statements of Internet Middleware
Corporation ("IMC") and to provide pro forma condensed combined financial
information not previously available.

ITEM 7.  FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS

         (a) Financial Statements of Businesses Acquired

                 Pursuant to paragraph (a)(4) of Item 7 of Form 8-K, the
         following financial statements were omitted from disclosure contained
         in the Registrant's Current Report on Form 8-K filed on March 28, 1997
         but are filed herewith:

                 Audited balance sheet of IMC as of December 31, 1996, the
         related audited statements of operations, shareholders' deficiency and
         cash flows for the period from inception (May 6, 1996) to December 31,
         1996 and a signed report of Deloitte & Touche LLP with respect to 
         such financial statements, which are attached as Exhibit 99.2 hereto.

         (b) Pro Forma Financial Information

                 Pursuant to paragraph (b)(2) of Item 7, the unaudited pro forma
         condensed combined balance sheet of the Registrant and IMC as of
         January 24, 1997 and the unaudited pro forma condensed combined
         statements of operations for the fiscal year ended April 30, 1996 and
         for the nine months ended January 24, 1997 are attached as Exhibit 99.3
         hereto.  The unaudited pro forma condensed combined financial
         statements give effect to the merger of the Registrant and IMC on a
         purchase accounting basis.  The pro forma condensed combined balance
         sheet assumes the merger took place on January 24, 1997 and combines
         the January 24, 1997 balance sheet of the Registrant with the January
         31, 1997 balance sheet of IMC. The pro forma condensed combined
         statement of operations for the fiscal year ended April 30, 1996
         assumes the merger took place as of the beginning of the fiscal year
         and combines the Registrant's historical results for the fiscal year
         ended April 30, 1996 (for which period IMC was not in operation) with
         pro forma adjustments.  The pro forma condensed combined statement of
         operations for the nine months ended January 24, 1997 assumes the
         merger took place as of the beginning of the most recently completed
         fiscal year and combines the Registrant's historical results for the
         nine months ended January 24, 1997 with the historical results of IMC
         for the period from inception (May 6, 1996) to January 31, 1997.   

                 The pro forma information is presented for illustrative
         purposes only and is not necessarily indicative of the operating
         results or financial position that would have occurred had the
         acquisition of IMC by the Registrant been consummated at the beginning
         of the periods presented, nor is it necessarily indicative of future
         operating results or financial position. These pro forma financial
         statements are based on and should be read in conjunction with the
         historical consolidated financial statements and the related notes
         thereto of the Registrant and IMC.



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         (a) Exhibits

         2.1+    Agreement and Plan of Reorganization, dated as of March 17,
                 1997, between the Registrant and IMC, a California corporation.

         2.2+    Agreement of Merger between the Registrant and IMC as filed 
                 with the California Secretary of State on March 17, 1997.

         2.3+    Stock Option Agreement between the Registrant and certain
                 former employees of IMC.
         
         23.1    Consent of Deloitte & Touche LLP.  
         
         99.1+   Press release of the Registrant, dated March 17, 1997,
                 announcing the completion of the Registrant's acquisition of
                 IMC.

         99.2    Audited balance sheet of IMC as of December 31, 1996, the 
                 related audited statements of operations, shareholders' 
                 deficiency and cash flows for the period from inception 
                 (May 6, 1996) to December 31, 1996 and a signed report of 
                 Deloitte & Touche LLP with respect to such financial 
                 statements.

         99.3    Unaudited pro forma condensed combined balance sheet of the
                 Registrant and IMC as of January 24, 1997 and the unaudited pro
                 forma condensed combined statements of operations of the
                 Registrant and IMC for the fiscal year ended April 30, 1996 and
                 for the nine months ended January 24, 1997.


         +       Previously filed



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                                   SIGNATURES

                 Pursuant to the requirements of the Securities Exchange Act of
1934, as amended, the Registrant has duly caused this report to be signed on
its behalf by the undersigned hereunto duly authorized.

                                               NETWORK APPLIANCE, INC.


Dated:  April 15, 1997                         By: /s/ JEFFRY R. ALLEN
                                                  ___________________________
                                                  Jeffry R. Allen, Vice
                                                  President Finance and
                                                  Operations,
                                                  Chief Financial Officer
                                                  (Principal Financial Officer)











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                                 EXHIBIT INDEX

                            

        EXHIBIT
        NUMBER                  DESCRIPTION OF DOCUMENT

         2.1+    Agreement and Plan of Reorganization, dated as of March 17,
                 1997, between the Registrant and IMC, a California corporation.

         2.2+    Agreement of Merger between the Registrant and IMC as filed 
                 with the California Secretary of State on March 17, 1997.

         2.3+    Stock Option Agreement between the Registrant and certain
                 former employees of IMC.
        
         23.1    Consent of Deloitte & Touche LLP.  
         
         99.1+   Press release of the Registrant, dated March 17, 1997,
                 announcing the completion of the Registrant's acquisition of
                 IMC.

         99.2    Audited balance sheet of IMC as of December 31, 1996, the 
                 related audited statements of operations, shareholders' 
                 deficiency and cash flows for the period from inception 
                 (May 6, 1996) to December 31, 1996 and a signed report of 
                 Deloitte & Touche LLP with respect to such financial 
                 statements.

         99.3    Unaudited pro forma condensed combined balance sheet of the
                 Registrant and IMC as of January 24, 1997 and the unaudited pro
                 forma condensed combined statements of operations of the
                 Registrant and IMC for the fiscal year ended April 30, 1996 and
                 for the nine months ended January 24, 1997.


         +       Previously filed



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