<PAGE>
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                               __________________


                                   FORM 10-Q/A

(MARK ONE)

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

                  FOR THE QUARTERLY PERIOD ENDED JUNE 27, 2003

                                       OR

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


             FOR THE TRANSITION PERIOD FROM __________ TO __________

                         COMMISSION FILE NUMBER: 0-9692


                                  TELLABS, INC.
             (Exact name of registrant as specified in its charter)


                 DELAWARE                                    36-3831568
         (State of Incorporation)                         (I.R.S. Employer
                                                        Identification No.)


      ONE TELLABS CENTER, 1415 W. DIEHL ROAD,
               NAPERVILLE, ILLINOIS                             60563
       (Address of Principal Executive Offices)              (Zip Code)

       Registrant's telephone number, including area code: (630) 378-8800

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 past 90 days. YES X  NO
                                      ---   ---

Indicate by check mark whether the registrant is an accelerated filer (as
defined in Rule 12b-2 of the Exchange Act). YES X  NO
                                               ---   ---

Common Shares, $.01 Par Value - 412,895,751 shares outstanding on June 27, 2003.


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The Company is filing this amendment on Form 10-Q/A for the quarter ended June
27, 2003 to file its Section 302 Certifications that were inadvertently omitted
in the original filing.

This amendment does not otherwise update any other information or disclosures
set forth in the original filing of the Quarterly Report on August 7, 2003.



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                                  TELLABS, INC.
                                      INDEX




CERTIFICATIONS


SIGNATURE



<PAGE>

                                 CERTIFICATIONS



I, Timothy J. Wiggins, certify that:

     1.   I have reviewed this quarterly report on Form 10-Q of Tellabs, Inc.;

     2.   Based on my knowledge, this quarterly report does not contain any
          untrue statement of a material fact or omit to state a material fact
          necessary to make the statements made, in light of the circumstances
          under which such statements were made, not misleading with respect to
          the period covered by this quarterly report;

     3.   Based on my knowledge, the financial statements, and other financial
          information included in this quarterly report, fairly present in all
          material respects the financial condition, results of operations and
          cash flows of the registrant as of, and for, the periods presented in
          this quarterly report;

     4.   The registrant's other certifying officers and I are responsible for
          establishing and maintaining disclosure controls and procedures (as
          defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant
          and have:

               a)   designed such disclosure controls and procedures to ensure
                    that material information relating to the registrant,
                    including its consolidated subsidiaries, is made known to us
                    by others within those entities, particularly during the
                    period in which this quarterly report is being prepared;

               b)   evaluated the effectiveness of the registrant's disclosure
                    controls and procedures as of a date within 90 days prior to
                    the filing date of this quarterly report (the "Evaluation
                    Date"); and

               c)   presented in this quarterly report our conclusions about the
                    effectiveness of the disclosure controls and procedures
                    based on our evaluation as of the Evaluation Date;

     5.   The registrant's other certifying officers and I have disclosed, based
          on our most recent evaluation, to the registrant's auditors and the
          audit committee of registrant's board of directors (or persons
          performing the equivalent functions):

               a)   all significant deficiencies in the design or operation of
                    internal controls which could adversely affect the
                    registrant's ability to record, process, summarize and
                    report financial data and have identified for the
                    registrant's auditors any material weaknesses in internal
                    controls; and

               b)   any fraud, whether or not material, that involves management
                    or other employees who have a significant role in the
                    registrant's internal controls; and


     6.   The registrant's other certifying officers and I have indicated in
          this quarterly report whether there were significant changes in
          internal controls or in other factors that could significantly affect
          internal controls subsequent to the date of our most recent
          evaluation, including any corrective actions with regard to
          significant deficiencies and material weaknesses.


Date: August 4, 2003

                                                     /S/ TIMOTHY J. WIGGINS
                                                     ------------------------
                                                     Timothy J. Wiggins
                                                     Chief Financial Officer
<PAGE>

I, Michael J. Birck, certify that:

     1.   I have reviewed this quarterly report on Form 10-Q of Tellabs, Inc.;

     2.   Based on my knowledge, this quarterly report does not contain any
          untrue statement of a material fact or omit to state a material fact
          necessary to make the statements made, in light of the circumstances
          under which such statements were made, not misleading with respect to
          the period covered by this quarterly report;

     3.   Based on my knowledge, the financial statements, and other financial
          information included in this quarterly report, fairly present in all
          material respects the financial condition, results of operations and
          cash flows of the registrant as of, and for, the periods presented in
          this quarterly report;

     4.   The registrant's other certifying officers and I are responsible for
          establishing and maintaining disclosure controls and procedures (as
          defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant
          and have:

               a)   designed such disclosure controls and procedures to ensure
                    that material information relating to the registrant,
                    including its consolidated subsidiaries, is made known to us
                    by others within those entities, particularly during the
                    period in which this quarterly report is being prepared;

               b)   evaluated the effectiveness of the registrant's disclosure
                    controls and procedures as of a date within 90 days prior to
                    the filing date of this quarterly report (the "Evaluation
                    Date"); and

               c)   presented in this quarterly report our conclusions about the
                    effectiveness of the disclosure controls and procedures
                    based on our evaluation as of the Evaluation Date;

     5.   The registrant's other certifying officers and I have disclosed, based
          on our most recent evaluation, to the registrant's auditors and the
          audit committee of registrant's board of directors (or persons
          performing the equivalent functions):

               a)   all significant deficiencies in the design or operation of
                    internal controls which could adversely affect the
                    registrant's ability to record, process, summarize and
                    report financial data and have identified for the
                    registrant's auditors any material weaknesses in internal
                    controls; and

               b)   any fraud, whether or not material, that involves management
                    or other employees who have a significant role in the
                    registrant's internal controls; and


     6.   The registrant's other certifying officers and I have indicated in
          this quarterly report whether there were significant changes in
          internal controls or in other factors that could significantly affect
          internal controls subsequent to the date of our most recent
          evaluation, including any corrective actions with regard to
          significant deficiencies and material weaknesses.



Date: August 4, 2003

                                                 /S/ MICHAEL J. BIRCK
                                                 ------------------------------
                                                 Michael J. Birck
                                                 Chief Executive Officer
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                                    SIGNATURE

Pursuant to the requirements of 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.

                                  TELLABS, INC.
                                  -------------
                                  (Registrant)



                                                 /S/ JAMES A. DITE
                                                 ------------------------------
                                                 James A. Dite
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)

                                                 August 8, 2003
                                                 (Date)