<PAGE>   1


                                   FORM 10-Q/A

                       SECURITIES AND EXCHANGE COMMISSION
                       ----------------------------------
                             Washington, D.C. 20549


Quarterly Report Under Section 13 or 15 (d) of the Securities Exchange Act of
1934


(Mark One)

[X]    QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
       EXCHANGE ACT OF 1934 (AMENDED)

For the quarterly period ended    JUNE 29, 1997
                                  -------------

                                       OR

[ ]    TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
       EXCHANGE ACT OF 1934

For the transition period from___________  to__________



For the Quarter ended   JUNE 29, 1997             Commission File Number 1-9434
                        -------------




                             PICTURETEL CORPORATION
             (Exact name of Registrant as specified in its charter)


          DELAWARE                                         04-2835972
          --------                                         ----------
(State or other jurisdiction of                            (I.R.S. Employer
incorporation or organization)                             Identification No.)

100 Minuteman Road, Andover, MA.                           01810
--------------------------------                           -----
(Address of Principal Executive Offices)                   (Zip Code)

Registrant's Telephone Number:                             978-292-5000
------------------------------                             ------------


Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15 (d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the Registrant
was required to file such reports), and (2) has been subject to such filing
requirements for the last 90 days.

                             Yes  X   No
                                 ---    ---

Indicate the number of shares outstanding of each of the issuer's classes of
common stock as of the latest practical date.

As of August 6, 1997, there were 34,471,233 issued and outstanding shares of
common stock of the registrant.



<PAGE>   2


                             PICTURETEL CORPORATION

                                    FORM 10-Q

                                      INDEX



NOTE: This Form 10-Q/A for the quarter ended June 29, 1997 is being filed
to correct a mathematical error in the "Consolidated Statements of Cash Flows"
for the six month period ended June 29, 1997, restated as stated in Form 10-Q/A
for the quarter ended June 29, 1997, filed on January 13, 1998. The "Purchase
of marketable securities" line under "Investing activities" changed from
(14,784) to (16,011). The "Additions to property and equipment" line, also under
"Investing activities", changed from (12,893) to (14,784). There are no other
changes to the Form 10-Q/A for the quarter ended June 29, 1997 as filed on
January 13, 1998. 
<TABLE>
<CAPTION>

PART I.   CONSOLIDATED FINANCIAL INFORMATION

<S>                                                                                                                      <C>

   Item 1. Consolidated Financial Statements:

           Consolidated Balance Sheets

                  June 29, 1997 and December 31, 1996.....................................................................3

           Consolidated Statements of Operations

                  Three and six months ended June 29, 1997 and June 29, 1996..............................................4

           Consolidated Statements of Cash Flows

                  Six months ended June 29, 1997 and June 29, 1996........................................................5

           Notes to Consolidated Financial Statements....................................................................6-9


   Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations........................10-13


PART II.  OTHER INFORMATION


   Item 1. Legal Proceedings.............................................................................................16

   Item 4. Submission of Matters to a Vote of Security Holders...........................................................16-17

   Item 5. Other Information.............................................................................................18

   Item 6. Exhibits and Reports on Form 8-K..............................................................................18

   Signatures............................................................................................................19
</TABLE>


                                       2



<PAGE>   3

                             PICTURETEL CORPORATION
                           Consolidated Balance Sheets
                             (Dollars in thousands)

<TABLE>
<CAPTION>

                                                                         June 29,         December 31,
                                                                           1997               1996
                                                                        (Restated)         (Restated)
                                  ASSETS
<S>                                                                     <C>                <C>      
Current assets:
     Cash and cash equivalents                                          $  42,980          $  63.333
     Marketable securities                                                 30,802             38,918
     Accounts receivable, less allowance for doubtful accounts
        of $3,712 in 1997 and $3,178 in 1996                              121,826            143,237
     Inventories, net (Note 3)                                             71,514             51,538
     Deferred taxes, net                                                    6,008              6,462
     Other current assets                                                  12,720              5,781
                                                                        ---------          ---------

     Total current assets                                                 285,850            309,269

     Marketable securities                                                   --                9,118
     Deferred taxes, net                                                    5,088              3,945
     Property and equipment, net                                           49,661             47,747
     Capitalized software costs, net                                       10,197              9,110
     Other assets                                                          12,239              7,065
                                                                        ---------          ---------
     Total assets                                                       $ 363,035          $ 386,254
                                                                        =========          =========

                      LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
     Short-term borrowings (Note 6)                                     $   1,946          $     519
     Accounts payable                                                      37,403             54,293
     Accrued compensation and benefits                                     10,621              8,906
     Accrued expenses                                                      20,771             20,538
     Current portion of capital lease obligations                           3,550              3,423
     Deferred revenue                                                      19,524             19,527
                                                                        ---------          ---------
     Total current liabilities                                             93,815            107,206

     Long-term borrowings (Note 6)                                          1,454              9,242
     Capital lease obligations                                              3,052              4,960

Stockholders' equity:

Preference stock, $.01 par value; 15,000,000 shares authorized;
     none  issued                                                            --                 --
Common stock, $.01 par value; 80,000,000 shares authorized;
    37,753,695 and 37,499,111 shares issued and outstanding in
    1997 and 1996, respectively                                               378                375
Additional paid-in capital                                                202,058            199,756
Retained earnings                                                          61,935             64,429
Cumulative translation adjustment                                            (170)              (602)
Unrealized gain on marketable securities, net                                 513                888
                                                                        ---------          ---------
     Total stockholders' equity                                           264,714            264,846
                                                                        ---------          ---------
Total liabilities and stockholders' equity                              $ 363,035          $ 386,254
                                                                        =========          =========
</TABLE>


The accompanying notes are an integral part of the consolidated financial
statements.

                                       3

<PAGE>   4


                             PICTURETEL CORPORATION
                      Consolidated Statements of Operations
                (Dollars in thousands, except per share amounts)
<TABLE>
<CAPTION>

                                                      Three Months Ended                 Six Months Ended
                                                      ------------------                 ----------------
                                                  June 29,           June 29,        June 29,           June 29,
                                                    1997              1996             1997               1996
                                                 (Restated)                         (Restated)

<S>                                              <C>                <C>              <C>                <C>     
Revenues                                         $ 117,966          $122,690         $ 239,901          $230,745

Cost of sales                                       66,271            61,664           129,469           116,748
                                                 ---------          --------         ---------          --------

Gross margin                                        51,695            61,026           110,432           113,997

Operating expenses:

     Selling, general and administrative            38,650            33,422            74,915            63,050

     Research and development                       20,424            15,124            41,358            30,003
                                                 ---------          --------         ---------          --------

     Total operating expenses                       59,074            48,546           116,273            93,053
                                                 ---------          --------         ---------          --------

Income (loss) from operations                       (7,379)           12,480            (5,841)           20,944

Interest income, net                                   686             1,102             1,577             2,179

Other income (expense), net                           (210)            1,099               194             1,665
                                                 ---------          --------         ---------          --------

Income (loss) before taxes                          (6,903)           14,681            (4,070)           24,788

Income tax expense (benefit)                        (2,003)            5,017            (1,181)            8,181
                                                 ---------          --------         ---------          --------

Net income (loss)                                $  (4,900)         $  9,664         $  (2,889)         $ 16,607
                                                 =========          ========         =========          ========

Net income (loss) per common and common
  equivalent share:                              $   (0.13)         $   0.24         $   (0.08)         $   0.42
                                                 =========          ========         =========          ========

Weighted average common and common
  equivalent shares outstanding:                    37,636            39,631            37,589            39,665
                                                 =========          ========         =========          ========
</TABLE>


The accompanying notes are an integral part of the consolidated financial
statements.

                                       4

<PAGE>   5


                             PICTURETEL CORPORATION
                      CONSOLIDATED STATEMENTS OF CASH FLOWS
                             (Dollars in thousands)
<TABLE>
<CAPTION>

                                                                                      Six Months Ended
                                                                                 June 29,          June 29,
                                                                                   1997              1996
                                                                                ----------         --------
                                                                                (Restated)

<S>                                                                              <C>               <C>     
Cash flows from operating activities:
   Net income ..........................................................         ($ 2,889)         $ 16,607
   Adjustments to reconcile net income to net cash provided by (used in)
  operating activities:
      Depreciation and amortization ....................................           15,526             9,930
      Deferred taxes, net ..............................................             (689)             --
      Other non-cash items .............................................             --                (346)

   Changes in operating assets and liabilities:
      Accounts receivable ..............................................           21,411           (14,485)
      Inventories ......................................................          (19,976)            7,033
      Other assets .....................................................          (11,355)             (907)
      Accounts payable .................................................          (16.890)            1,171
      Accrued compensation and benefits and accrued expenses ...........            3,114             2,312
      Accrued income taxes .............................................           (1,166)            4,778
      Deferred revenue .................................................               (3)           (1,067)
                                                                                 --------          --------

Net cash provided by (used in) operating activities ....................          (12,917)           25,026

Cash flows from investing activities:
   Purchase of marketable securities ...................................          (16,011)          (11,167)
   Proceeds from marketable securities .................................           32,871            14,314
   Additions to property and equipment .................................          (14,784)          (19,260)
   Capitalized software costs ..........................................           (3,743)           (3,195)
   Purchase of other assets ............................................             (758)           (3,000)
                                                                                 --------          --------

Net cash provided by (used in) investing activities ....................           (2,425)          (22,308)

Cash flows from financing activities:
   Change in short-term borrowings .....................................            1,427              (830)
   Payments on long-term borrowings ....................................           (7,788)           (2,211)
   Principal payments under capital lease obligations ..................           (1,781)           (1,414)
   Proceeds from exercise of stock options .............................            1,206             6,681
   Proceeds from stock purchase plan ...................................            1,099               883
                                                                                 --------          --------

Net cash provided by (used in) financing activities ....................           (5,837)            3,109

Adjustment to conform fiscal year of Multilink .........................              394              --

Effect of exchange rate changes on cash ................................              432               460
                                                                                 --------          --------

Net increase (decrease) in cash and cash equivalents ...................          (20,353)            6,287
Cash and cash equivalents at beginning of period .......................           63,333            39,587
                                                                                 --------          --------
Cash and cash equivalents at end of  period ............................         $ 42,980          $ 45,874
                                                                                 ========          ========

Supplemental cash flow information:
   Interest paid .......................................................         $    589          $    296
   Income taxes paid ...................................................         $  1,758          $    954
</TABLE>

The accompanying notes are an integral part of the consolidated financial
statements.


                                       5


<PAGE>   6


                             PICTURETEL CORPORATION

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1.   MANAGEMENT'S REPRESENTATION

     As permitted by the rules of the Securities and Exchange Commission
applicable to Quarterly Reports on Form 10-Q, these notes are condensed and do
not contain all the disclosures required by generally accepted accounting
principles. Reference should be made to the consolidated financial statements
and related notes included in the Company's Annual Report on Form 10-K for the
year ended December 31, 1996, as filed with the Securities and Exchange
Commission on March 28, 1997, as amended by Form 10-K/A to reflect the
restatement of the financial results for the year ended December 31, 1996 (See
Note 2 to Notes to Consolidated Financial Statements).

     In the opinion of the management of PictureTel Corporation, the
accompanying unaudited consolidated financial statements contain all
adjustments(consisting of normal, recurring adjustments, except as discussed in
Notes 2, 4 and 5 to Notes to Consolidated Financial Statements) necessary to
present fairly the Company's financial position at June 29, 1997 and the results
of operations and changes in cash flows for the three and six months ended June
29, 1997.

     The results disclosed in the Consolidated Balance Sheets at June 29,1997
and the Consolidated Statements of Operations and Consolidated Statements of
Cash Flows for the three and six months ended June 29, 1997 are not necessarily
indicative of the results to be expected for the full year.

     The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period. As a result of lower demand for the Company's products and the
resulting ongoing evaluation of the business and future spending levels, the
financial statements include significant estimates of the net realizable value
of accounts receivable, inventory and capitalized software as well as the future
tax benefit of deferred tax assets and the amount of certain contingent
liabilities. Actual results could differ from those estimates.

     The financial statements and footnotes included in this Form 10-Q/A have
been restated to reflect the restatement of financial results and pooling of
interests described in Notes 2 and 4 to Notes to Consolidated Financial
Statements.

2.   RESTATEMENT OF FINANCIAL STATEMENTS

     On September 19, 1997, after the Company's reexamination (with assistance
from its outside auditors) of leasing and other indirect channel transactions,
the Company announced that it would reverse revenue related to certain of these
transactions and, as a result, the Company intended to restate its financial
statements for the third and fourth quarters of 1996 and the first quarter of
1997. On November 13, 1997, after completion of its reexamination, the Company
announced that it would also restate the second quarter of 1997. The
restatements were required to reverse product sales recorded which contained
rights of return, contingent liabilities, payment contingencies, payment
uncertainties or product sales for which delivery did not occur at the end of
the period. The restatements were also required to record such product sales in
the period in which the rights of return lapsed, contingencies or uncertainties
were resolved, or delivery was completed. Certain transactions which were
reversed have not been re-recorded as revenues in later periods. The financial
statements and related notes to consolidated financial statements set forth in
this Form 10-Q/A reflect all such restatements. A summary of the impact of such
restatements for the three and six months ended June 29, 1997 is as follows:
<TABLE>
<CAPTION>

                                                                           Three Months Ended
                                                                              June 29, 1997
                                                                   Previously               As
                                                                    Reported             Restated
                                                                              ($000's)
<S>                                                                 <C>                  <C>     
     Revenues                                                       $119,304             $117,966
     Gross margin                                                     52,580               51,695
     Income (loss) before taxes                                       (5,617)              (6,903)
     Income tax expense.(benefit)                                     (1,946)              (2,003)
     Net income (loss)                                                (3,671)              (4,900)
     Net income per common and common equivalent share              $  (0.10)            $  (0.13)
</TABLE>


                                       6


<PAGE>   7

<TABLE>
<CAPTION>

                                                                          Six Months Ended
                                                                             June 29, 1997
                                                                   Previously                As
                                                                    Reported              Restated
                                                                               ($000's)
<S>                                                                 <C>                   <C>     
     Revenues                                                       $242,922              $239,901
     Gross margin                                                    111,847               110,432
     Income (loss) before taxes                                      (1,854)                (4,070)
     Income tax expense (benefit)                                      (676)                (1,181)
     Net income (loss)                                               (1,178)                (2,889)
     Net income per common and common
              equivalent share                                      $ (0.03)              $  (0.08)
</TABLE>

<TABLE>
<CAPTION>
                                                                          Six Months Ended
                                                                             June 29, 1997
                                                                   Previously                As
                                                                    Reported              Restated
                                                                               ($000's)
<S>                                                                 <C>                   <C>     
     Total assets                                                   $367,584              $363,035
     Total liabilities                                              $ 96,996              $ 98,321
     Total stockholders' equity                                     $270,588              $264,714
</TABLE>


3.   INVENTORIES

     Inventories consist of the following (in thousands):
<TABLE>
<CAPTION>

                                        June 29,           December 31,
                                          1997                1996
                                          ----                ----
                                       (Restated)          (Restated)

<S>                                      <C>                <C>    
     Purchased Parts                     $ 7,204            $ 6,409
     Work in Process                       3,564              2,018
     Finished Goods                       60,746             43,111
                                         -------            -------
                                         $71,514            $51,538
                                         =======            =======
</TABLE>


4.   ACQUISITION OF MULTILINK, INC.

     On July 22, 1997, the Company acquired all of the common stock of
MultiLink, Inc. (MultiLink) in a transaction accounted for as a pooling of
interests. MultiLink develops, manufactures and markets software and hardware
that enable users at two or more sites to participate in face-to-face meetings.
The Company issued 3,578,026 shares of common stock in exchange for 6,389,332
shares of MultiLink common stock at a ratio of one share of MultiLink common
stock to 0.56 shares of the Company's common stock. The accompanying
consolidated financial statements for all periods prior to the acquisition have
been restated to include the results of operations, financial position and cash
flows of MultiLink. The revenues, net loss, and loss per share for the Company,
prior to restatement for the pooling of interests, would have been $110,900,000,
($4,210,000) and ($0.12) for the three months ended June 29, 1997 and
$227,439,000, ($1,513,000) and ($0.04) for the six months ended June 29, 1997,
respectively. The following information presents certain income statement data
of the separate companies for periods prior to the acquisition which for these
purposes has been assumed to have occurred on June 29, 1997:
<TABLE>
<CAPTION>

                                                  Six Months Ended
                                                       June 29,
                                                1997            1996
                                                      ($000's)
<S>                                           <C>            <C>     
     Revenues:
              PictureTel                      $227,439       $221,083
              MultiLink                         12,462          9,662
     Net income (loss):
              PictureTel                      $(1,513)       $ 15,957
              MultiLink                        (1,376)            650
</TABLE>


                                       7

<PAGE>   8


     In conjunction with the acquisition, MultiLink's fiscal year end has been
changed from September 30 to December 31 to conform to the Company's fiscal year
end. As a result, the financial statements for the nine months ended September
28, 1996 and 1997 include the results of operations and financial position of
MultiLink for the nine months ended June 30, 1996 and the nine months ended
September 30, 1997, respectively. Accordingly, MultiLink's results of operations
and financial position for the quarter ended December 31, 1996 excluded from the
financial statements are as follows (in 000's):
<TABLE>

<S>                                                            <C>   
     Revenues................................................. $6,613

     Total cost of sales and operating expenses............... $5,918

     Net income............................................... $  394
</TABLE>

     The net income of $394,000 for the quarter ended December 31, 1996 has been
credited directly to retained earnings.

     Intercompany sales from MultiLink to the Company were insignificant and
have been eliminated in consolidation.

     Costs associated with the acquisition of $2,561,000 have been charged to
operations in the three and nine month periods ended September 28, 1997,
subsequent to the periods presented in this filing. These costs principally
relate to investment banking, accounting and legal advisory fees and severance
expense.

5.   LITIGATION

     A.  Datapoint Litigation

     In December 1993, PictureTel was sued by Datapoint Corporation in the
United States District Court for the Northern District of Texas. Datapoint
alleges that certain of the Company's products infringe patent rights allegedly
owned by Datapoint. Datapoint has been joined as plaintiff by John Frassanito
and David Monroe, two individuals who claim to have rights to Datapoint's
patents. The plaintiffs seek approximately $100 million to $190 million in
damages for alleged past infringement and an injunction against alleged future
infringement. The Company believes that it has meritorious defenses to the
allegations of the complaint and is vigorously defending against the lawsuit.
The case had been scheduled for trial on October 6, 1997; however, the trial was
delayed by the Court until early 1998.

     In the event the Company is found to be infringing a valid patent or
patents, the Company could be required to pay damages for past infringement and
cease the sale of products incorporating the infringing feature (or be required
to obtain a license and pay royalties with respect to such patents). There can
be no assurance that the Company will prevail. The Company believes that an
adverse outcome of the lawsuit would have a material adverse effect on the
business or the financial position, results of operations and cash flows of the
Company.

     B.  Class Action Litigation

     Since September 23, 1997, seven class action shareholders' complaints have
been filed against the Company, Norman E. Gaut, Chairman of the Board and Chief
Executive Officer, and Les Strauss, the former Vice President and Chief
Financial Officer, in the United States District Court for the District of
Massachusetts. The plaintiffs, who brought these actions on behalf of themselves
and others similarly situated, are: (1) Faith Egli, Civil Action No.
97-12135-DPW; (2) Jerome H. Lipman, IRA, Civil Action No. 97-12238-DPW; (3)
Daniel Frucher, Civil Action No. 97-12310-DPW; (4) Edmond J. Proulx and James
Harris, Civil Action No. 97-12345-DPW; (5) Marvin Barab and Thomas J. Curley,
Civil Action No. 97-12338-DPW; (6) Mark Szen and Nancy Szen, Civil Action No.
97-12439-DPW; and (7) Michael D. Kugler, Civil Action No. 97-12537 PBS.

     The Complaints were filed following the Company's announcement on September
19, 1997 that it would restate its financial results for the first quarter of
fiscal 1997 and the last two quarters of fiscal 1996. The Complaints allege that
the defendants violated Sections 10(b) and 20(a) of the Securities and Exchange
Act of 1934 and Rule 10b-5, promulgated thereunder, during the period from
October 17, 1996 through September 18 or 19, 1997, inclusive, through the
alleged preparation and dissemination of materially false and misleading
financial statements which artificially inflated the prices of PictureTel common
stock. Each Complaint seeks to recover an unspecified amount of damages,
including attorneys' and experts' fees and expenses. The Company is currently
investigating the allegations in the Complaints and will respond to the
allegations in a timely fashion when responses become due. No discovery has
occurred and the Company expresses no opinion as to the likely outcome.


                                       8

<PAGE>   9

6.   DEBT

     The Company has an unsecured revolving credit agreement with a borrowing
limit of $40,000,000. The Company's borrowings consist primarily of letters of
credit pledged against future facility lease obligations. At June 29, 1997,
there was $3,400,000 in borrowings and $30,713,000 in standby letters of credit
outstanding under the revolving credit agreement. The agreement contains certain
financial covenants, including the maintenance of certain ratios. As a result of
the net loss incurred for the three months ended June 28, 1997 and for the third
quarter of 1997, (subsequent to the period covered by this filing) the Company
was not in compliance with the debt covenants associated with its borrowings at
September 28, 1997. The Company has obtained a waiver of the covenant violation.
The covenant violation will result in the need for the Company to obtain a
waiver for at least each of the next four fiscal quarters. There can be no
assurance that the Company will obtain such a waiver.


                                       9


<PAGE>   10



                                    SIGNATURE
                                    ---------


     Pursuant to the Securities Exchange Act of 1934, the registrant has duly
caused this report to be signed on its behalf by the undersigned thereunto duly
authorized.






                             PICTURETEL CORPORATION





               /s/ Richard B. Goldman
               ----------------------------------------------
               Richard B. Goldman
               Vice President, Chief Financial Officer, Secretary and Treasurer
               (Principal Financial and Accounting Officer)
               January 20, 1998.




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