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                                                                     EXHIBIT 4.3

                           TRANSACTION GRANT AGREEMENT
                              WITH LEONARD G. MILKE

                                CYBERONICS, INC.

                       STAND-ALONE STOCK OPTION AGREEMENT

I.   NOTICE OF STOCK OPTION GRANT

     LEONARD G. MILKE

     You have been granted a Nonstatutory Stock Option to purchase Common Stock
of the Company, subject to the terms and conditions of this Agreement, as
follows:

Date of Grant                                      March 23, 2000

Vesting Commencement Date                          March 23, 2000

Exercise Price per Share                           $17.125

Total Number of Shares Granted                     100,000

Total Exercise Price                               $1,712,500

Term/Expiration Date:                              March 23, 2010

Vesting Schedule:

     This Option shall vest and may be exercised, in whole or in part, in
accordance with the following schedule:

     1/60th of the Shares subject to the Option shall vest each month after the
Vesting Commencement Date, so that the Option shall be fully vested five (5)
years from the Date of Grant, subject to the Optionee continuing to be a Service
Provider on such dates.

     Termination Period

     This Option may be exercised for ninety (90) days after Optionee ceases to
be a Service Provider in accordance with Section 7 of this Agreement. Upon the
death or Disability of the Optionee, this Option may be exercised for twelve
(12) months after the Optionee ceases to be a Service Provider in accordance
with Sections 8 and 9 of this Agreement. In no event shall this Option be
exercised later than the Term/Expiration Date provided.

II.  AGREEMENT

     1. Definitions. As used herein, the following definitions shall apply:

          (a) "Agreement" means this stock option agreement between the Company
and Optionee evidencing the terms and conditions of this Option.

          (b) "Applicable Laws" means the requirements relating to the
administration of stock options under U.S. state corporate laws, U.S. federal
and state securities laws, the Code, any stock exchange or quotation system on


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which the Common Stock is listed or quoted and the applicable laws of any
foreign country or jurisdiction that may apply to this Option.

          (c) "Board" means the Board of Directors of the Company or any
committee of the Board that has been designated by the Board to administer this
Agreement.

          (d) "Code" means the Internal Revenue Code of 1986, as amended.

          (e) "Common Stock" means the common stock of the Company.

          (f) "Company" means Cyberonics, Inc., a Delaware corporation.

          (g) "Consultant" means any person, including an advisor, engaged by
the Company or a Parent or Subsidiary to render services to such entity.

          (h) "Director" means a member of the Board.

          (i) "Disability" means total and permanent disability as defined in
Section 22(e)(3) of the Code.

          (j) "Employee" means any person, including Officers and Directors,
employed by the Company or any Parent or Subsidiary of the Company. A Service
Provider shall not cease to be an Employee in the case of (i) any leave of
absence approved by the Company or (ii) transfers between locations of the
Company or between the Company, its Parent, any Subsidiary, or any successor.
Neither service as a Director nor payment of a director's fee by the Company
shall be sufficient to constitute "employment" by the Company.

          (k) "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

          (l) "Fair Market Value" means, as of any date, the value of Common
Stock determined as follows:

               (1) If the Common Stock is listed on any established stock
exchange or a national market system, including without limitation the Nasdaq
National Market or The Nasdaq SmallCap Market of The Nasdaq Stock Market, its
Fair Market Value shall be the closing sales price for such stock (or the
closing bid, if no sales were reported) as quoted on such exchange or system on
the day of determination, as reported in The Wall Street Journal or such other
source as the Administrator deems reliable;

               (2) If the Common Stock is regularly quoted by a recognized
securities dealer but selling prices are not reported, its Fair Market Value
shall be the mean between the high bid and low asked prices for the Common Stock
on the day of determination; or

               (3) In the absence of an established market for the Common Stock,
the Fair Market Value thereof shall be determined in good faith by the Board.

          (m) "Nonstatutory Stock Option" means an Option not intended to
qualify as an incentive stock option within the meaning of Section 422 of the
Code and the regulations promulgated thereunder.

          (n) "Notice of Grant" means a written notice, in Part I of this
Agreement, evidencing certain the terms and conditions of this Option grant. The
Notice of Grant is part of the Option Agreement.

          (o) "Officer" means a person who is an officer of the Company within
the meaning of Section 16 of the Exchange Act and the rules and regulations
promulgated thereunder.

          (p) "Option" means this stock option.


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          (q) "Optioned Stock" means the Common Stock subject to this Option.

          (r) "Optionee" means the person named in the Notice of Grant or such
person's successor.

          (s) "Parent" means a "parent corporation," whether now or hereafter
existing, as defined in Section 424(e) of the Code.

          (t) "Service Provider" means an Employee, Director or Consultant.

          (u) "Share" means a share of the Common Stock, as adjusted in
accordance with Section 10 of this Agreement.

          (v) "Subsidiary" means a "subsidiary corporation", whether now or
hereafter existing, as defined in Section 424(f) of the Code.

     2. Grant of Option. The Board hereby grants to the Optionee named in the
Notice of Grant attached as Part I of this Agreement the Option to purchase the
number of Shares, as set forth in the Notice of Grant, at the exercise price per
share set forth in the Notice of Grant (the "Exercise Price"), subject to the
terms and conditions of this Agreement.

     3. Exercise of Option.

          (a) Right to Exercise. This Option is exercisable during its term in
accordance with the Vesting Schedule set out in the Notice of Grant and the
applicable provisions of this Agreement.

          (b) Method of Exercise. This Option is exercisable by delivery of an
exercise notice, in the form attached as Exhibit A (the "Exercise, Notice"),
which shall state the election to exercise the Option, the number of Shares in
respect of which the Option is being exercised (the "Exercised Shares"), and
such other representations and agreements as may be required by the Company. The
Exercise Notice shall be completed by the Optionee and delivered to Secretary of
the Company. The Exercise Notice shall be accompanied by payment of the
aggregate Exercise Price as to all Exercised Shares. This Option shall be deemed
to be exercised upon receipt by the Company of such fully executed Exercise
Notice accompanied by such aggregate Exercise Price.

          (c) Legal Compliance. No Shares shall be issued pursuant to the
exercise of this Option unless such issuance and exercise complies with
Applicable Laws. Assuming such compliance, for income tax purposes the Exercised
Shares shall be considered transferred to the Optionee on the date the Option is
exercised with respect to such Exercised Shares.

     4. Method of Payment. Payment of the aggregate Exercise Price shall be by
any of the following, or a combination thereof, at the election of the Optionee:

          (a) cash or check;

          (b) promissory note;

          (c) consideration received by the Company under a cashless exercise
program implemented by the Company; or

          (d) surrender of other Shares, provided Shares acquired directly from
the Company, (i) have been owned by the Optionee for more than six (6) months on
the date of surrender, and (ii) have a Fair Market Value on the date of
surrender equal to the aggregate Exercise Price of the Exercised Shares.


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     5. Non-Transferability of Option. This Option may not be transferred in any
manner otherwise than by will or by the laws of descent or distribution and may
be exercised during the lifetime of Optionee only by the Optionee. The terms of
this Agreement shall be binding upon the executors, administrators, heirs,
successors and assigns of the Optionee.

     6. Term of Option. This Option may be exercised only within the term set
out in the Notice of Grant, and may be exercised during such term only in
accordance with the terms of this Agreement.

     7. Termination of Relationship as a Service Provider. If the Optionee
ceases to be a Service Provider (other than for death or Disability), this
Option may be exercised for a period of ninety (90) days after the date of such
termination (but in no event later than the expiration date of this Option as
set forth in the Notice of Grant) to the extent that the Option is vested on the
date of such termination. To the extent that the Optionee does not exercise this
Option within the time specified herein, the Option shall terminate.

     8. Disability of Optionee. If the Optionee ceases to be a Service Provider
as a result of the Optionee's Disability, this Option may be exercised for a
period of twelve (12) months after the date of such termination (but in no event
later than the expiration date of this Option as set forth in the Notice of
Grant) to the extent that the Option is vested on the date of such termination.
To the extent that Optionee does not exercise this Option within the time
specified herein, the Option shall terminate.

     9. Death of Optionee. If the Optionee dies while a Service Provider, the
Option may be exercised at any time within twelve (12) months following the date
of death (but in no event later than the expiration date of this Option as set
forth in the Notice of Grant), by the Optionee's estate or by a person who
acquired the right to exercise the Option by bequest or inheritance, but only to
the extent that the Optionee was entitled to exercise the Option at the date of
death. If, after death, the Optionee's estate or a person who acquired the right
to exercise the Option by bequest or inheritance does not exercise the Option
within the time specified herein, the Option shall terminate.

     10. Adjustments Upon Changes in Capitalization, Dissolution, Merger or
Asset Sale.

          (a) Changes in Capitalization. Subject to any required action by the
stockholders of the Company, the number of shares of Common Stock covered by
this Option, as well as the price per share of Common Stock covered by this
Option, shall be proportionately adjusted for any increase or decrease in the
number of issued shares of Common Stock resulting from a stock split, reverse
stock split, stock dividend, combination or reclassification of the Common
Stock, or any other increase or decrease in the number of issued shares of
Common Stock effected without receipt of consideration by the Company; provided,
however, that conversion of any convertible securities of the Company shall not
be deemed to have been "effected without receipt of consideration." Such
adjustment shall be made by the Board, whose determination in that respect shall
be final, binding and conclusive. Except as expressly provided herein, no
issuance by the Company of shares of stock of any class, or securities
convertible into shares of stock of any class, shall affect, and no adjustment
by reason thereof shall be made with respect to, the number or price of shares
of Common Stock subject to this Option.

          (b) Dissolution or Liquidation. In the event of the proposed
dissolution or liquidation of the Company, the Board shall notify Optionee as
soon as practicable prior to the effective date of such proposed transaction.
The Board in its discretion may provide for the Optionee to have the right to
exercise his or her Option until ten (10) days prior to such transaction as to
all of the Optioned Stock covered thereby, including Shares as to which the
Option would not otherwise be exercisable. To the extent it has not been
previously exercised, the Option will terminate immediately prior to the
consummation of such proposed.

          (c) Merger or Asset Sale. In the event of a merger of the Company with
or into another corporation, or the sale of substantially all of the assets of
the Company, the Option shall be assumed or an equivalent option substituted by
the successor corporation or a Parent or Subsidiary of the successor
corporation. In the event that the successor corporation refuses to assume or
substitute for the Option, the Optionee shall fully vest in and have the right


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to exercise the Option as to all of the Optioned Stock, including Shares as to
which it would not otherwise be vested or exercisable. If the Option becomes
fully vested and exercisable in lieu of assumption or substitution in the event
of a merger or sale of assets, the Board shall notify the Optionee in writing or
electronically that the Option shall be fully exercisable for a period of
fifteen (15) days from the date of such notice, and the Option shall terminate
upon the expiration of such period. For the purposes of this paragraph, the
Option shall be considered assumed if, following the merger or sale of assets,
the option confers the right to purchase or receive, for each Share of Optioned
Stock subject to the Option immediately prior to the merger or sale of assets,
the consideration (whether stock, cash, or other securities or property)
received in the merger or sale of assets by holders of Common Stock for each
Share held on the effective date of the transaction (and if holders were offered
a choice of consideration, the type of consideration chosen by the holders of a
majority of the outstanding Shares); provided, however, that if such
consideration received in the merger or sale of assets is not solely common
stock of the successor corporation or its Parent, the Administrator may, with
the consent of the successor corporation, provide for the consideration to be
received upon the exercise of the Option, for each Share of Optioned Stock
subject to the Option, to be solely common stock of the successor corporation or
its Parent equal in fair market value to the per share consideration received by
holders of Common Stock in the merger or sale of assets.

          (d) Change of Control. In the event of a Change of Control (as defined
below), the Optionee shall fully vest in and have the right to exercise the
Option as to all of the Optioned Stock, including Shares as to which it would
not otherwise be vested or exercisable, and any Company reacquisition option
applicable to any Shares acquired upon exercise of an Option shall lapse as to
all such Shares. If an Option becomes fully vested and exercisable as the result
of a Change of Control, the Administrator shall notify the Optionee in writing
or electronically prior to the Change of Control that the Option shall be fully
vested and exercisable for a period of fifteen (15) days from the date of such
notice, and the Option shall terminate upon the expiration of such period. For
purposes of this Plan, a "Change of Control" means the happening of any of the
following events:

               (1) When any "person," as such term is used in Sections 13(d) and
14(d) of the Exchange Act, other than the Company, a subsidiary of the Company
or a Company employee benefit plan, including any trustee of such plan acting as
trustee, is or becomes the "beneficial owner" (as defined in Rule 13d-3 under
the Exchange Act), directly or indirectly, of securities of the Company
representing fifty percent (50%) or more of the combined voting power of the
Company's then outstanding securities entitled to vote generally in the election
of directors; or

               (2) The shareholders of the Company approve a merger or
consolidation of the Company with any other corporation, other than a merger or
consolidation which would result in the voting securities of the Company
outstanding immediately prior thereto continuing to represent (either by
remaining outstanding or by being converted into voting securities of the
surviving entity) more than fifty percent (50%) of the total voting power
represented by the voting securities of the Company or such surviving entity
outstanding immediately after such merger or consolidation, or the shareholders
of the Company approve an agreement for the sale or disposition by the Company
of all or substantially all the Company's assets; or

               (3) A change in the composition of the Board of Directors of the
Company, as a result of which fewer than a majority of the directors are
Incumbent Directors. "Incumbent Directors" shall mean directors who either (A)
are directors of the Company as of the date the Plan is approved by the
shareholders, or (B) are elected, or nominated for election, to the Board of
Directors of the Company with the affirmative votes of at least a majority of
the Incumbent Directors at the time of such election or nomination (but shall
not include an individual whose election or nomination is in connection with an
actual or threatened proxy contest relating to the election of directors to the
Company).

     11. Notices. Any notice to be given to the Company hereunder shall be in
writing and shall be addressed to the Company at its then current principal
executive office or to such other address as the Company may hereafter designate
to the Optionee by notice as provided in this Section. Any notice to be given to
the Optionee hereunder shall be addressed to the Optionee at the address set
forth beneath his signature hereto, or at such other address as the Optionee


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may hereafter designate to the Company by notice as provided herein. A notice
shall be deemed to have been duly given when personally delivered or mailed by
registered or certified mail to the party entitled to receive it.

     12. Withholding Taxes. Optionee agrees to make appropriate arrangements
with the Company (or the Parent or Subsidiary employing or retaining Optionee)
for the satisfaction of all federal, state, and local income and employment tax
withholding requirements applicable to the Option exercise. Optionee
acknowledges and agrees that the Company may refuse to honor the exercise and
refuse to deliver Shares if such withholding amounts are not delivered at the
time of exercise.

     13. Entire Agreement; Governing Law. This Agreement constitutes the entire
agreement of the parties with respect to the subject matter hereof and
supersedes in its entirety all prior undertakings and agreements of the Company
and Optionee with respect to the subject matter hereof, and may not be modified
adversely to the Optionee's interest except by means of a writing signed by the
Company and Optionee. This agreement is governed by the internal substantive
laws, but not the choice of law rules, of Texas.

     14. NO GUARANTEE OF CONTINUED SERVICE. OPTIONEE ACKNOWLEDGES AND AGREES
THAT THE VESTING OF SHARES PURSUANT TO THE VESTING SCHEDULE HEREOF IS EARNED
ONLY BY CONTINUING AS A SERVICE PROVIDER AT THE WILL OF THE COMPANY (AND NOT
THROUGH THE ACT OF BEING HIRED, BEING GRANTED AN OPTION OR PURCHASING SHARES
HEREUNDER). OPTIONEE FURTHER ACKNOWLEDGES AND AGREES THAT THIS AGREEMENT, THE
TRANSACTIONS CONTEMPLATED HEREUNDER AND THE VESTING SCHEDULE SET FORTH HEREIN DO
NOT CONSTITUTE AN EXPRESS OR IMPLIED PROMISE OF CONTINUES ENGAGEMENT AS A
SERVICE PROVIDER FOR THE VESTING PERIOD, FOR ANY PERIOD, OR AT ALL, AND SHALL
NOT INTERFERE WITH OPTIONEE'S RIGHT OR THE COMPANY'S RIGHT TO TERMINATE
OPTIONEE'S RELATIONSHIP AS A SERVICE PROVIDER AT ANY TIME, WITH OR WITHOUT
CAUSE.


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     By your signature and the signature of the Company's representative below,
you and the Company agree that this Option is granted under and governed by the
terms and conditions of this Agreement. Optionee has reviewed this Agreement in
its entirety, has had an opportunity to obtain the advice of counsel prior to
executing this Agreement and fully understands all provisions of this Agreement.
Optionee hereby agrees to accept as binding, conclusive and final all decisions
or interpretations of the Board upon any questions relating to this Agreement.
Optionee further agrees to notify the Company upon any change in the residence
address indicated below.

OPTIONEE                                     CYBERONICS, INC.


/s/ Leonard G. Milke                         /s/ Robert P. Cummins
------------------------------------         -----------------------------------
Leonard G. Milke                             Robert P. Cummins
                                             President & Chief Executive Officer


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                                                                       EXHIBIT A


                                CYBERONICS, INC.

                                 EXERCISE NOTICE

Cyberonics, Inc.
16511 Space Center Boulevard #600
Houston, Texas 77062

Attention:

     1. Exercise of Option. Effective as of today, ________________ , 20___ ,
the undersigned ("Purchaser") hereby elects to purchase _______________ shares
(the "Shares") of the Common Stock of Cyberonics, Inc. (the "Company") under and
pursuant to the Stock Option Agreement dated [___________ ] (the "Option
Agreement"). The purchase price for the Shares shall be [$____________ ], as
required by the Option Agreement.

     2. Delivery of Payment. Purchaser herewith delivers to the Company the full
purchase price for the Shares.

     3. Representations of Purchaser. Purchaser acknowledges that Purchaser has
received, read and understood the Option Agreement and agrees to abide by and be
bound by their terms and conditions.

     4. Rights as Shareholder. Until the issuance (as evidenced by the
appropriate entry on the books of the Company or of a duly authorized transfer
agent of the Company) of the Shares, no right to vote or receive dividends or
any other rights as a stockholder shall exist with respect to the Optioned
Stock, notwithstanding the exercise of the Option. The Shares so acquired shall
be issued to the Optionee as soon as practicable after exercise of the Option.
No adjustment will be made for a dividend or other right for which the record
date is prior to the date of issuance, except as provided in Section 10 of the
Option Agreement.

     5. Tax Consultation. Purchaser understands that Purchaser may suffer
adverse tax consequences as a result of Purchaser's purchase or disposition of
the Shares. Purchaser represents that Purchaser has consulted with any tax
consultants Purchaser deems advisable in connection with the purchase or
disposition of the Shares and that Purchaser is not relying on the Company for
any tax advice.

     6. Successors and Assigns. The Company may assign any of its rights under
this Exercise Notice to single or multiple assignees, and this Exercise Notice
shall inure to the benefit of the successors and assigns of the Company. Subject
to the restrictions on transfer herein set forth, this Exercise Notice shall be
binding upon Optionee and his or her heirs, executors, administrators,
successors and assigns.

     7. Interpretation. Any dispute regarding the interpretation of this
Exercise Notice shall be submitted by Optionee or by the Company forthwith to
the Board which shall review such dispute at its next regular meeting. The
resolution of such a dispute by the Board shall be final and binding on all
parties.

     8. Entire Agreement: Governing Law. The Option Agreement is incorporated
herein by reference. This Agreement, and the Option Agreement constitute the
entire agreement of the parties with respect to the subject matter hereof and
supersede in their entirety all prior undertakings and agreements of the Company
and Purchaser with respect to the subject matter hereof, and may not be modified
adversely to the Purchaser's interest except by means of a writing signed by the
Company and Purchaser. This agreement is governed by the internal substantive
laws, but not the choice of law rules, of Texas.

Submitted by:                                Accepted by:


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OPTIONEE                                     CYBERONICS, INC.


--------------------------------             -----------------------------------
Signature


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Print Name


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Address                                      Address


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                                             Date Received:
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