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                                                                 EXHIBIT 10.d

                          REGISTRATION RIGHTS AGREEMENT                  


                  This Registration Rights Agreement (this "AGREEMENT") is made
and entered into as of April 23, 1998, among PLC Systems Inc., a corporation
organized and existing under the laws of British Columbia, Canada (the
"COMPANY"), Southbrook International Investments, Ltd., a British Virgin Islands
corporation ("SOUTHBROOK"), Brown Simpson Strategic Growth Fund, L.P., a New
York limited partnership ("BROWN SIMPSON LP"), and Brown Simpson Strategic
Growth Fund, Ltd., a Cayman Islands exempt company ("BROWN SIMPSON LIMITED").
Southbrook, Brown Simpson LP and Brown Simpson Limited are each referred to
herein as a "PURCHASER" and collectively as the "PURCHASERS."

                  This Agreement is made pursuant to the Convertible Debenture
Purchase Agreement, dated as of the date hereof among the Company and the
Purchasers (the "PURCHASE AGREEMENT").

                  The Company and the Purchasers hereby agree as follows:

         1.       DEFINITIONS

                  Capitalized terms used and not otherwise defined herein shall
have the meanings given such terms in the Purchase Agreement. As used in this
Agreement, the following terms shall have the following meanings:

                  "ADVICE" shall have meaning set forth in Section 3(o).

                  "AFFILIATE" means, with respect to any Person, any other
Person that directly or indirectly controls or is controlled by or under common
control with such Person. For the purposes of this definition, "CONTROL," when
used with respect to any Person, means the possession, direct or indirect, of
the power to direct or cause the direction of the management and policies of
such Person, whether through the ownership of voting securities, by contract or
otherwise; and the terms of "AFFILIATED," "CONTROLLING" and "CONTROLLED" have
meanings correlative to the foregoing.

                  "BUSINESS DAY" means any day except Saturday, Sunday and any
day which shall be a legal holiday or a day on which banking institutions in the
state of New York generally are authorized or required by law or other
government actions to close.

                  "CLOSING DATE" shall have the meaning set forth in the 
Purchase Agreement.

                  "COMMISSION" means the Securities and Exchange Commission.

                  "COMMON STOCK" means the Company's Common Stock, without par 
value.
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                  "DEBENTURES" means Tranche 1 and Tranche 2 Convertible
Debentures of the Company issued to the Purchasers pursuant to the Purchase
Agreement.

                  "EFFECTIVENESS DATE" means (i) with respect to the
Registration Statement to be filed with respect to the Tranche 1 Debentures, the
90th day following the Tranche 1 Closing Date and (ii) with respect to the
Registration Statement to be filed with respect to the Tranche 2 Debentures, the
90th day following the Tranche 2 Closing Date.

                  "EFFECTIVENESS PERIOD" shall have the meaning set forth in 
Section 2(a).

                  "EXCHANGE ACT" means the Securities Exchange Act of 1934, as 
amended.

                  "FILING DATE" means (i) with respect to the shares of Common
Stock issuable upon conversion of the Tranche 1 Debentures and exercise of the
Tranche 1 Warrants, the 30th day following the Tranche 1 Closing Date and (ii)
with respect to the shares of Common Stock issuable upon conversion of the
Tranche 2 Debentures and exercise of the Tranche 2 Warrants, the 30th day
following the Tranche 2 Closing Date.

                  "HOLDER" or "HOLDERS" means the holder or holders, as the case
may be, from time to time of Registrable Securities.

                  "INDEMNIFIED PARTY" shall have the meaning set forth in 
Section 5(c).

                  "INDEMNIFYING PARTY" shall have the meaning set forth in 
Section 5(c).

                  "LOSSES" shall have the meaning set forth in Section 5(a).

                  "PERSON" means an individual or a corporation, partnership,
trust, incorporated or unincorporated association, joint venture, limited
liability company, joint stock company, government (or an agency or political
subdivision thereof) or other entity of any kind.


                  "PROCEEDING" means an action, claim, suit, investigation or
proceeding (including, without limitation, an investigation or partial
proceeding, such as a deposition), whether commenced or threatened.

                  "PROSPECTUS" means the prospectus included in the Registration
Statement (including, without limitation, a prospectus that includes any
information previously omitted from a prospectus filed as part of an effective
registration statement in reliance upon Rule 430A promulgated under the
Securities Act), as amended or supplemented by any prospectus supplement, with
respect to the terms of the offering of any portion of the Registrable
Securities covered by the Registration Statement, and all other amendments and
supplements to the Prospectus, including post-effective amendments, and all
material incorporated by reference or deemed to be incorporated by reference in
such Prospectus.

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                  "REGISTRABLE SECURITIES" means (a) with respect to the
Registration Statement to be filed after the Tranche 1 Closing, the shares of
Common Stock issuable upon (i) conversion of the Tranche 1 Debentures and (ii)
exercise of the Tranche 1 Warrants issued by the Company to the Purchasers, (b)
with respect to the Registration Statement to be filed after the Tranche 2
Closing, the shares of Common Stock issuable upon (i) conversion of the Tranche
2 Debentures and (ii) exercise of the Tranche 2 Warrants issued by the Company
to the Purchasers; PROVIDED, HOWEVER that in order to account for the fact that
the number of shares of Common Stock that are issuable upon conversion of
Debentures is determined in part upon the market price of the Common Stock at
the time of conversion, in the case of each of (a) and (b), Registrable
Securities shall include (but not be limited to) a number of shares of Common
Stock equal to no less than the sum of (1) two times the number of shares of
Common Stock into which the applicable tranche of Debentures are convertible,
assuming such conversion occurred on the particular Closing Date for such
tranches of Debentures and (2) the number of shares of Common Stock issuable
upon exercise in full of the Warrants issued at the applicable Closing Date
described herein, or such other number of shares of Common Stock as agreed to by
the parties to the Purchase Agreement; PROVIDED, FURTHER that the Company shall
not be obligated to register, (A) in respect of the Tranche 1 Closing, in excess
of the sum of (i) 640,000 shares of Common Stock issuable upon conversion of
Tranche 1 Debentures and (ii) 4,864 shares of Common Stock issuable upon
exercise of Tranche 1 Warrants and (B) in respect of the Tranche 2 Closing, in
excess of the sum of (i) 200% of the number of shares of Common Stock issuable
upon conversion in full of the Tranche 2 Debentures and (ii) a number of shares
of Common Stock sufficient to permit exercise in full of the Tranche 2 Warrants
(whether such Warrants are issued on the Tranche 2 Closing Date or the Tranche 2
Closing Expiration Date).

                  "REGISTRATION STATEMENT" means the registration statements
contemplated by Section 2(a) (and any additional Registration Statements
contemplated in the definition of Registrable Securities), including (in each
case) the Prospectus, amendments and supplements to such registration statement
or Prospectus, including pre- and post-effective amendments, all exhibits
thereto, and all material incorporated by reference or deemed to be incorporated
by reference in such registration statement.

                  "RULE 144" means Rule 144 promulgated by the Commission
pursuant to the Securities Act, as such Rule may be amended from time to time,
or any similar rule or regulation hereafter adopted by the Commission having
substantially the same effect as such Rule.

                  "RULE 158" means Rule 158 promulgated by the Commission
pursuant to the Securities Act, as such Rule may be amended from time to time,
or any similar rule or regulation hereafter adopted by the Commission having
substantially the same effect as such Rule.

                  "RULE 415" means Rule 415 promulgated by the Commission
pursuant to the Securities Act, as such Rule may be amended from time to time,
or any similar rule or regulation hereafter adopted by the Commission having
substantially the same effect as such Rule.

                  "SECURITIES ACT" means the Securities Act of 1933, as amended.

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                  "SPECIAL COUNSEL" means any special counsel to the Holders,
for which the Holders will be reimbursed by the Company pursuant to Section 4.

                  "UNDERWRITTEN REGISTRATION OR UNDERWRITTEN OFFERING" means a
registration in connection with which securities of the Company are sold to an
underwriter for reoffering to the public pursuant to an effective registration
statement.

         2.       SHELF REGISTRATION

                  (a) On or prior to each applicable Filing Date the Company
shall prepare and file with the Commission a "Shelf" Registration Statement
covering all Registrable Securities for an offering to be made on a continuous
basis pursuant to Rule 415. The Registration Statement shall be on Form S-3
(except if otherwise directed by the Holders of a majority in interest of the
applicable Registrable Securities in accordance herewith or if the Company is
not then eligible to register for resale the Registrable Securities on Form S-3,
in which case such registration shall be on another appropriate form in
accordance herewith). The Company shall (i) not permit any securities other than
the Registrable Securities to be included in the Registration Statement and (ii)
use its best efforts to cause the Registration Statement to be declared
effective under the Securities Act as promptly as possible after the filing
thereof, but in any event prior to the Effectiveness Date, and to keep such
Registration Statement continuously effective under the Securities Act until the
date which is two years after the date that such Registration Statement is
declared effective by the Commission or such earlier date when all Registrable
Securities covered by such Registration Statement have been sold or may be sold
without volume restrictions pursuant to Rule 144(k) as determined by the counsel
to the Company pursuant to a written opinion letter, addressed to the Company's
transfer agent to such effect (the "EFFECTIVENESS PERIOD"); PROVIDED, HOWEVER,
that the Company shall not be deemed to have used its best efforts to keep the
Registration Statement effective during the Effectiveness Period if it
voluntarily takes any action that would result in the Holders not being able to
sell the Registrable Securities covered by such Registration Statement during
the Effectiveness Period, unless such action is required under applicable law or
the Company has filed a post-effective amendment to the Registration Statement
and the Commission has not declared it effective.

                  (b) If the Holders of a majority of the Registrable Securities
so elect, an offering of Registrable Securities pursuant to the Registration
Statement may be effected on one occasions in the form of an Underwritten
Offering. In such event, and if the managing underwriters advise the Company and
such Holders in writing that in their opinion the amount of Registrable
Securities proposed to be sold in such Underwritten Offering exceeds the amount
of Registrable Securities which can be sold in such Underwritten Offering, there
shall be included in such Underwritten Offering the amount of such Registrable
Securities which in the opinion of such managing underwriters can be sold, and
such amount shall be allocated PRO RATA among the Holders proposing to sell
Registrable Securities in such Underwritten Offering.

                  (c) If any of the Registrable Securities are to be sold in an
Underwritten Offering, the investment banker in interest that will administer
the offering will be selected by the Holders of a majority of the Registrable
Securities included in such offering upon

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consultation  with the Company.  No Holder may  participate in any  Underwritten
Offering  hereunder  unless  such  Person  (i)  agrees  to sell its  Registrable
Securities on the basis provided in any underwriting  agreements approved by the
Persons entitled  hereunder to approve such  arrangements and (ii) completes and
executes  all  questionnaires,  powers of  attorney,  indemnities,  underwriting
agreements and other documents required under the terms of such arrangements.

         3.       REGISTRATION PROCEDURES

                  In connection with the Company's registration obligations
hereunder, the Company shall:

                  (a) Prepare and file with the Commission on or prior to each
applicable Filing Date, a Registration Statement on Form S-3 (or such other form
if directed by the Holders in connection with an Underwritten Offering hereunder
or if the Company is not then eligible to register for resale the Registrable
Securities on Form S-3, in which case such registration shall be on another
appropriate form in accordance herewith) in accordance with the method or
methods of distribution thereof as specified by the Holders (except if otherwise
directed by the Holders), and cause the Registration Statement to become
effective and remain effective as provided herein; PROVIDED, HOWEVER, that not
less than five (5) Business Days prior to the filing of the Registration
Statement or any related Prospectus or any amendment or supplement thereto
(including any document that would be incorporated or deemed to be incorporated
therein by reference), the Company shall (i) furnish to the Holders, their
Special Counsel and any managing underwriters, copies of all such documents
proposed to be filed, which documents (other than those incorporated or deemed
to be incorporated by reference) will be subject to the review of such Holders,
their Special Counsel and such managing underwriters, and (ii) cause its
officers and directors, counsel and independent certified public accountants to
respond to such inquiries as shall be necessary, in the reasonable opinion of
respective counsel to such Holders and such underwriters, to conduct a
reasonable investigation within the meaning of the Securities Act. The Company
shall not file the Registration Statement or any such Prospectus or any
amendments or supplements thereto to which the Holders of a majority of the
Registrable Securities, their Special Counsel, or any managing underwriters,
shall reasonably object in writing within three (3) Business Days of their
receipt thereof.

                  (b) (i) Prepare and file with the Commission such amendments,
including post-effective amendments, to the Registration Statement as may be
necessary to keep the Registration Statement continuously effective as to the
applicable Registrable Securities for the Effectiveness Period and prepare and
file with the Commission such additional Registration Statements in order to
register for resale under the Securities Act all of the Registrable Securities;
(ii) cause the related Prospectus to be amended or supplemented by any required
Prospectus supplement, and as so supplemented or amended to be filed pursuant to
Rule 424 (or any similar provisions then in force) promulgated under the
Securities Act; (iii) respond as promptly as practicable to any comments
received from the Commission with respect to the Registration Statement or any
amendment thereto and promptly provide the Holders true and complete copies of
all correspondence from and to the Commission relating to the Registration
Statement; and (iv) comply with the provisions of the Securities Act and the
Exchange Act with respect to the

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disposition of all Registrable  Securities covered by the Registration Statement
during  the  applicable  period  in  accordance  with the  intended  methods  of
disposition by the Holders thereof set forth in the Registration Statement as so
amended or in such Prospectus as so supplemented.

                  (c) Notify the Holders of Registrable Securities to be sold,
their Special Counsel and any managing underwriters immediately (and, in the
case of (i)(A) below, not less than five (5) days prior to such filing) and (if
requested by any such Person) confirm such notice in writing no later than one
(1) Business Day following the day (i)(A) when a Prospectus or any Prospectus
supplement or post-effective amendment to the Registration Statement is proposed
to be filed; (B) when the Commission notifies the Company whether there will be
a "review" of such Registration Statement and whenever the Commission comments
in writing on such Registration Statement and (C) with respect to the
Registration Statement or any post-effective amendment, when the same has become
effective; (ii) of any request by the Commission or any other Federal or state
governmental authority for amendments or supplements to the Registration
Statement or Prospectus or for additional information; (iii) of the issuance by
the Commission of any stop order suspending the effectiveness of the
Registration Statement covering any or all of the Registrable Securities or the
initiation of any Proceedings for that purpose; (iv) if at any time any of the
representations and warranties of the Company contained in any agreement
(including any underwriting agreement) contemplated hereby ceases to be true and
correct in all material respects; (v) of the receipt by the Company of any
notification with respect to the suspension of the qualification or exemption
from qualification of any of the Registrable Securities for sale in any
jurisdiction, or the initiation or threatening of any Proceeding for such
purpose; and (vi) of the occurrence of any event that makes any statement made
in the Registration Statement or Prospectus or any document incorporated or
deemed to be incorporated therein by reference untrue in any material respect or
that requires any revisions to the Registration Statement, Prospectus or other
documents so that, in the case of the Registration Statement or the Prospectus,
as the case may be, it will not contain any untrue statement of a material fact
or omit to state any material fact required to be stated therein or necessary to
make the statements therein, in light of the circumstances under which they were
made, not misleading.

                  (d) Use its best efforts to avoid the issuance of, or, if
issued, obtain the withdrawal of (i) any order suspending the effectiveness of
the Registration Statement or (ii) any suspension of the qualification (or
exemption from qualification) of any of the Registrable Securities for sale in
any jurisdiction, at the earliest practicable moment.

                  (e) If requested by any managing underwriter or the Holders of
a majority in interest of the Registrable Securities to be sold in connection
with an Underwritten Offering, (i) promptly incorporate in a Prospectus
supplement or post-effective amendment to the Registration Statement such
information as such managing underwriters and such Holders reasonably agree
should be included therein and (ii) make all required filings of such Prospectus
supplement or such post-effective amendment as soon as practicable after the
Company has received notification of the matters to be incorporated in such
Prospectus supplement or post-effective amendment; provided, HOWEVER, that the
Company shall not be required to take any action pursuant to this Section 3(e)
that would, in the opinion of counsel for the Company, violate applicable law or
be materially detrimental to the business prospects of the Company.

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                  (f) Furnish to each Holder, their Special Counsel and any
managing underwriters, without charge, at least one conformed copy of each
Registration Statement and each amendment thereto, including financial
statements and schedules, all documents incorporated or deemed to be
incorporated therein by reference, and all exhibits to the extent requested by
such Person (including those previously furnished or incorporated by reference)
promptly after the filing of such documents with the Commission.

                  (g) Promptly deliver to each Holder, their Special Counsel,
and any underwriters, without charge, as many copies of the Prospectus or
Prospectuses (including each form of prospectus) and each amendment or
supplement thereto as such Persons may reasonably request; and the Company
hereby consents to the use of such Prospectus and each amendment or supplement
thereto by each of the selling Holders and any underwriters in connection with
the offering and sale of the Registrable Securities covered by such Prospectus
and any amendment or supplement thereto.

                  (h) Prior to any public offering of Registrable Securities,
use its best efforts to register or qualify or cooperate with the selling
Holders, any underwriters and their Special Counsel in connection with the
registration or qualification (or exemption from such registration or
qualification) of such Registrable Securities for offer and sale under the
securities or Blue Sky laws of such jurisdictions within the United States as
any Holder or underwriter requests in writing, to keep each such registration or
qualification (or exemption therefrom) effective during the Effectiveness Period
and to do any and all other acts or things necessary or advisable to enable the
disposition in such jurisdictions of the Registrable Securities covered by a
Registration Statement; PROVIDED, HOWEVER, that the Company shall not be
required to qualify generally to do business in any jurisdiction where it is not
then so qualified or to take any action that would subject it to general service
of process in any such jurisdiction where it is not then so subject or subject
the Company to any material tax in any such jurisdiction where it is not then so
subject.

                  (i) Cooperate with the Holders and any managing underwriters
to facilitate the timely preparation and delivery of certificates representing
Registrable Securities to be sold pursuant to a Registration Statement, which
certificates shall be free of all restrictive legends, and to enable such
Registrable Securities to be in such denominations and registered in such names
as any such managing underwriters or Holders may request at least two Business
Days prior to any sale of Registrable Securities.

                  (j) Upon the occurrence of any event contemplated by Section
3(c)(vi), as promptly as practicable, prepare a supplement or amendment,
including a post-effective amendment, to the Registration Statement or a
supplement to the related Prospectus or any document incorporated or deemed to
be incorporated therein by reference, and file any other required document so
that, as thereafter delivered, neither the Registration Statement nor such
Prospectus will contain an untrue statement of a material fact or omit to state
a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading.

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                  (k) Use its best efforts to cause all Registrable Securities
relating to such Registration Statement to be listed on the American Stock
Exchange and any other securities exchange, quotation system, market or
over-the-counter bulletin board, if any, on which similar securities issued by
the Company are then listed as and when required pursuant to the Purchase
Agreement.

                  (l) Enter into such agreements (including an underwriting
agreement in form, scope and substance as is customary in Underwritten
Offerings) and take all such other actions in connection therewith (including
those reasonably requested by any managing underwriters and the Holders of a
majority of the Registrable Securities being sold) in order to expedite or
facilitate the disposition of such Registrable Securities, and whether or not an
underwriting agreement is entered into, (i) make such representations and
warranties to such Holders and such underwriters as are customarily made by
issuers to underwriters in underwritten public offerings, and confirm the same
if and when requested; (ii) in the case of an Underwritten Offering obtain and
deliver copies thereof to the managing underwriters, if any, of opinions of
counsel to the Company and updates thereof addressed to each such underwriter,
in form, scope and substance reasonably satisfactory to any such managing
underwriters covering the matters customarily covered in opinions requested in
Underwritten Offerings and such other matters as may be reasonably requested by
such underwriters; (iii) immediately prior to the effectiveness of the
Registration Statement, and, in the case of an Underwritten Offering, at the
time of delivery of any Registrable Securities sold pursuant thereto, obtain and
deliver copies to the Holders and the managing underwriters, if any, of "cold
comfort" letters and updates thereof from the independent certified public
accountants of the Company (and, if necessary, any other independent certified
public accountants of any subsidiary of the Company or of any business acquired
by the Company for which financial statements and financial data is, or is
required to be, included in the Registration Statement), addressed to each
selling Holder and each of the underwriters, if any, in form and substance as
are customary in connection with Underwritten Offerings; (iv) if an underwriting
agreement is entered into, the same shall contain indemnification provisions and
procedures no less favorable to the selling Holders and the underwriters, if
any, than those set forth in Section 6 (or such other provisions and procedures
acceptable to the managing underwriters, if any, and holders of a majority of
Registrable Securities participating in such Underwritten Offering; and (v)
deliver such documents and certificates as may be reasonably requested by the
Holders of a majority of the Registrable Securities being sold, their Special
Counsel and any managing underwriters to evidence the continued validity of the
representations and warranties made pursuant to clause 3(l)(i) above and to
evidence compliance with any customary conditions contained in the underwriting
agreement or other agreement entered into by the Company.

                  (m) Make available for inspection by the selling Holders, a
representative of such Holders, an underwriter participating in any disposition
of Registrable Securities, and an attorney or accountant retained by such
selling Holders or underwriters, at the offices where normally kept, during
reasonable business hours, all financial and other records, pertinent corporate
documents and properties of the Company and its subsidiaries, and cause the
officers, directors, agents and employees of the Company and its subsidiaries to
supply all information in

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each case reasonably requested by any such Holder, representative,  underwriter,
attorney or accountant in connection with the Registration Statement;  PROVIDED,
HOWEVER, that any information that is determined in good faith by the Company in
writing  to be of a  confidential  nature  at  the  time  of  delivery  of  such
information shall be kept confidential by such Persons, unless (i) disclosure of
such information is required by court or administrative order or is necessary to
respond  to  inquiries  of  regulatory  authorities;  (ii)  disclosure  of  such
information, in the opinion of counsel to such Person, is required by law; (iii)
such  information  becomes  generally  available  to the public  other than as a
result of a disclosure  or failure to  safeguard  by such  Person;  or (iv) such
information  becomes  available  to such  Person  from a source  other  than the
Company  and  such  source  is  not  known  by  such  Person  to be  bound  by a
confidentiality agreement with the Company.

                  (n) Comply with all applicable rules and regulations of the
Commission and make generally available to its security holders earning
statements satisfying the provisions of Section 11(a) of the Securities Act and
Rule 158 not later than 45 days after the end of any 12-month period (or 90 days
after the end of any 12-month period if such period is a fiscal year) (i)
commencing at the end of any fiscal quarter in which Registrable Securities are
sold to underwriters in a firm commitment or best efforts Underwritten Offering
and (ii) if not sold to underwriters in such an offering, commencing on the
first day of the first fiscal quarter of the Company after the effective date of
the Registration Statement, which statement shall cover said 12-month period, or
end shorter periods as is consistent with the requirements of Rule 158.

                  (o) The Company may require each selling Holder to furnish to
the Company such information regarding the distribution of such Registrable
Securities as is required by law to be disclosed in the Registration Statement
and the Company may exclude from such registration the Registrable Securities of
any such Holder who unreasonably fails to furnish such information within a
reasonable time after receiving such request.

                  If the Registration Statement refers to any Holder by name or
otherwise as the holder of any securities of the Company, then such Holder shall
have the right to require (if such reference to such Holder by name or otherwise
is not required by the Securities Act or any similar Federal statute then in
force) the deletion of the reference to such Holder in any amendment or
supplement to the Registration Statement filed or prepared subsequent to the
time that such reference ceases to be required.

                  The Purchaser covenants and agrees that (i) it will not sell
any Registrable Securities under the Registration Statement until it has
received copies of the Prospectus as then amended or supplemented as
contemplated in Section 3(g) and notice from the Company that such Registration
Statement and any post-effective amendments thereto have become effective as
contemplated by Section 3(c) and (ii) the Purchaser and its officers, directors
or Affiliates, if any, will comply with the prospectus delivery requirements of
the Securities Act as applicable to them in connection with sales of Registrable
Securities pursuant to the Registration Statement.

                  Each Holder agrees by its acquisition of such Registrable
Securities that, upon receipt of a notice from the Company of the occurrence of
any event of the kind described in

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Section 3(c)(ii),  3(c)(iii),  3(c)(iv),  3(c)(v) or 3(c)(vi),  such Holder will
forthwith  discontinue  disposition of such  Registrable  Securities  until such
Holder's  receipt of the copies of the  supplemented  Prospectus  and/or amended
Registration  Statement  contemplated by SECTION 3(j), or until it is advised in
writing (the "ADVICE") by the Company that the use of the applicable  Prospectus
may be resumed,  and, in either case,  has received  copies of any additional or
supplemental  filings  that are  incorporated  or deemed to be  incorporated  by
reference in such Prospectus or Registration Statement.

                  If (a) there is material non-public information regarding the
Company which the Board reasonably determines not to be in the Company's best
interest to disclose and which the Company is not otherwise required to
disclose, or (b) there is a significant business opportunity (including but not
limited to the acquisition or disposition of assets (other than in the ordinary
course of business) or any merger, consolidation, tender offer or other similar
transaction) available to the Company which the Board reasonably determines not
to be in the Company's best interest to disclose, then the Company may postpone
or suspend filing or effectiveness of a registration statement for a period not
to exceed 20 consecutive days, provided that the Company may not postpone or
suspend its obligation under this Section for more than 60 days in the aggregate
during any 12 month period; PROVIDED, HOWEVER, that no such postponement of
suspension shall be permitted for consecutive 20 day periods, arising out of the
same set as of facts, circumstances or transactions.

                  4.       REGISTRATION EXPENSES

                  (a) All fees and expenses incident to the performance of or
compliance with this Agreement by the Company shall, except as and to the extent
specified in Section 4(b), be borne by the Company whether or not pursuant to an
Underwritten Offering and whether or not the Registration Statement is filed or
becomes effective and whether or not any Registrable Securities are sold
pursuant to the Registration Statement. The fees and expenses referred to in the
foregoing sentence shall include, without limitation, (i) all registration and
filing fees (including, without limitation, fees and expenses (A) with respect
to filings required to be made with The American Stock Exchange and each other
securities exchange or market on which Registrable Securities are required
hereunder to be listed and (B) in compliance with state securities or Blue Sky
laws (including, without limitation, fees and disbursements of counsel for the
Holders in connection with Blue Sky qualifications of the Registrable Securities
and determination of the eligibility of the Registrable Securities for
investment under the laws of such jurisdictions as the managing underwriters, if
any, or the Holders of a majority of Registrable Securities may designate)),
(ii) printing expenses (including, without limitation, expenses of printing
certificates for Registrable Securities and of printing prospectuses if the
printing of prospectuses is requested by the managing underwriters, if any, or
by the holders of a majority of the Registrable Securities included in the
Registration Statement), (iii) messenger, telephone and delivery expenses, (iv)
fees and disbursements of counsel for the Company and Special Counsel for the
Holders, in the case of the Special Counsel, to a maximum amount of $5,000, (v)
Securities Act liability insurance, if the Company so desires such insurance,
and (vi) fees and expenses of all other Persons retained by the Company in
connection with the consummation of the transactions contemplated by this
Agreement. In addition, the Company

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shall be  responsible  for all of its internal  expenses  incurred in connection
with  the  consummation  of the  transactions  contemplated  by  this Agreement
(including,  without  limitation,  all salaries and expenses of its officers and
employees  performing  legal or  accounting  duties),  the expense of any annual
audit,  the fees and  expenses  incurred in  connection  with the listing of the
Registrable Securities on any securities exchange as required hereunder.

                  (b) If the Holders require an Underwritten Offering pursuant
to the terms hereof, the Company shall be responsible for all costs, fees and
expenses in connection therewith, except for the fees and disbursements of the
underwriters (including any underwriting commissions and discounts and other
expenses charged by the underwriters) and their legal counsel and accountants
(which shall be borne by the Holders). Therefore, in such circumstances the
Holder shall bear the expenses of the fees and disbursements of any legal
counsel or accounting firm retained by the underwriters in connection with such
Underwritten Offering and the costs of any determination (but not filing) by the
underwriters of the eligibility of the Registrable Securities for investment
under the applicable state securities laws. By way of illustration which is not
intended to diminish from the provisions of Section 4(a), the Holders shall not
be responsible for, and the Company shall be required to pay the fees or
disbursements incurred by the Company (including by its legal counsel and
accountants) in connection with, the preparation and filing of a Registration
Statement and related Prospectus for such offering, the maintenance of such
Registration Statement in accordance with the terms hereof, the listing of the
Registrable Securities in accordance with the requirements hereof, and printing
expenses incurred to comply with the requirements hereof.

         5.       INDEMNIFICATION

                  (a) INDEMNIFICATION BY THE COMPANY. The Company shall,
notwithstanding any termination of this Agreement, indemnify and hold harmless
each Holder, the officers, directors, agents (including any underwriters
retained by such Holder in connection with the offer and sale of Registrable
Securities), brokers (including brokers who offer and sell Registrable
Securities as principal as a result of a pledge or any failure to perform under
a margin call of Common Stock), investment advisors and employees of each of
them, each Person who controls any such Holder (within the meaning of Section 15
of the Securities Act or Section 20 of the Exchange Act) and the officers,
directors, agents and employees of each such controlling Person, to the fullest
extent permitted by applicable law, from and against any and all losses, claims,
damages, liabilities, costs (including, without limitation, costs of preparation
and attorneys' fees) and expenses (collectively, "LOSSES"), as incurred, arising
out of or relating to any untrue or alleged untrue statement of a material fact
contained in the Registration Statement, any Prospectus or any form of
prospectus or in any amendment or supplement thereto or in any preliminary
prospectus, or arising out of or relating to any omission or alleged omission of
a material fact required to be stated therein or necessary to make the
statements therein (in the case of any Prospectus or form of prospectus or
supplement thereto, in light of the circumstances under which they were made)
not misleading, except to the extent, but only to the extent, that such untrue
statements or omissions are based solely upon information regarding such Holder
furnished in writing to the Company by or on behalf of such Holder expressly for
use therein, or to the extent that such information relates to such Holder or
such Holder's proposed method of

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distribution of Registrable  Securities and was reviewed and expressly  approved
in writing by such Holder expressly for use in the Registration Statement,  such
Prospectus or such form of Prospectus or in any amendment or supplement thereto.
The Company  shall  notify the Holders  promptly of the  institution,  threat or
assertion of any Proceeding of which the Company is aware in connection with the
transactions contemplated by this Agreement.

                  (b) INDEMNIFICATION BY HOLDERS. Each Holder shall, severally
and not jointly, indemnify and hold harmless the Company, the directors,
officers, agents and employees, each Person who controls the Company (within the
meaning of Section 15 of the Securities Act and Section 20 of the Exchange Act),
and the directors, officers, agents or employees of such controlling Persons, to
the fullest extent permitted by applicable law, from and against all Losses (as
determined by a court of competent jurisdiction in a final judgment not subject
to appeal or review) arising solely out of or based solely upon any untrue
statement of a material fact contained in the Registration Statement, any
Prospectus, or any form of prospectus, or arising solely out of or based solely
upon any omission of a material fact required to be stated therein or necessary
to make the statements therein not misleading to the extent, but only to the
extent, that such untrue statement or omission is contained in any information
so furnished in writing by such Holder to the Company specifically for inclusion
in the Registration Statement or such Prospectus or to the extent that such
information relates to such Holder or such Holder's proposed method of
distribution of Registrable Securities and was reviewed and expressly approved
in writing by such Holder expressly for use in the Registration Statement, such
Prospectus or such form of Prospectus. In no event shall the liability of any
selling Holder hereunder be greater in amount than the dollar amount of the net
proceeds received by such Holder upon the sale of the Registrable Securities
giving rise to such indemnification obligation.

                  (c) CONDUCT OF INDEMNIFICATION PROCEEDINGS. If any Proceeding
shall be brought or asserted against any Person entitled to indemnity hereunder
(an "INDEMNIFIED PARTY"), such Indemnified Party promptly shall notify the
Person from whom indemnity is sought (the "INDEMNIFYING PARTY") in writing, and
the Indemnifying Party shall assume the defense thereof, including the
employment of counsel reasonably satisfactory to the Indemnified Party and the
payment of all fees and expenses incurred in connection with defense thereof;
provided, that the failure of any Indemnified Party to give such notice shall
not relieve the Indemnifying Party of its obligations or liabilities pursuant to
this Agreement, except (and only) to the extent that it shall be finally
determined by a court of competent jurisdiction (which determination is not
subject to appeal or further review) that such failure shall have proximately
and materially adversely prejudiced the Indemnifying Party.

                  An Indemnified Party shall have the right to employ separate
counsel in any such Proceeding and to participate in the defense thereof, but
the fees and expenses of such counsel shall be at the expense of such
Indemnified Party or Parties unless: (1) the Indemnifying Party has agreed in
writing to pay such fees and expenses; or (2) the Indemnifying Party shall have
failed promptly to assume the defense of such Proceeding and to employ counsel
reasonably satisfactory to such Indemnified Party in any such Proceeding; or (3)
the named parties to any such Proceeding (including any impleaded parties)
include both such Indemnified Party and the Indemnifying Party, and such
Indemnified Party shall have been advised by counsel that a

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conflict of interest is likely to exist if the same  counsel  were to  represent
such  Indemnified  Party and the  Indemnifying  Party (in  which  case,  if such
Indemnified  Party notifies the Indemnifying  Party in writing that it elects to
employ  separate  counsel  at  the  expense  of  the  Indemnifying   Party,  the
Indemnifying  Party shall not have the right to assume the  defense  thereof and
such  counsel  shall  be  at  the  expense  of  the  Indemnifying   Party).  The
Indemnifying Party shall not be liable for any settlement of any such Proceeding
effected  without its written  consent,  which consent shall not be unreasonably
withheld.  No Indemnifying Party shall, without the prior written consent of the
Indemnified Party, effect any settlement of any pending Proceeding in respect of
which any  Indemnified  Party is a party,  unless  such  settlement  includes an
unconditional  release of such  Indemnified  Party from all  liability on claims
that are the subject matter of such Proceeding.

                  All fees and expenses of the Indemnified Party (including
reasonable fees and expenses to the extent incurred in connection with
investigating or preparing to defend such Proceeding in a manner not
inconsistent with this Section) shall be paid to the Indemnified Party, as
incurred, within 10 Business Days of written notice thereof to the Indemnifying
Party (regardless of whether it is ultimately determined that an Indemnified
Party is not entitled to indemnification hereunder; PROVIDED, that the
Indemnifying Party may require such Indemnified Party to undertake to reimburse
all such fees and expenses to the extent it is finally judicially determined
that such Indemnified Party is not entitled to indemnification hereunder).

                  (d) CONTRIBUTION. If a claim for indemnification under Section
5(a) or 5(b) is unavailable to an Indemnified Party because of a failure or
refusal of a governmental authority to enforce such indemnification in
accordance with its terms (by reason of public policy or otherwise), then each
Indemnifying Party, in lieu of indemnifying such Indemnified Party, shall
contribute to the amount paid or payable by such Indemnified Party as a result
of such Losses, in such proportion as is appropriate to reflect the relative
fault of the Indemnifying Party and Indemnified Party in connection with the
actions, statements or omissions that resulted in such Losses as well as any
other relevant equitable considerations. The relative fault of such Indemnifying
Party and Indemnified Party shall be determined by reference to, among other
things, whether any action in question, including any untrue or alleged untrue
statement of a material fact or omission or alleged omission of a material fact,
has been taken or made by, or relates to information supplied by, such
Indemnifying Party or Indemnified Party, and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
action, statement or omission. The amount paid or payable by a party as a result
of any Losses shall be deemed to include, subject to the limitations set forth
in Section 5(c), any reasonable attorneys' or other reasonable fees or expenses
incurred by such party in connection with any Proceeding to the extent such
party would have been indemnified for such fees or expenses if the
indemnification provided for in this Section was available to such party in
accordance with its terms.

                  The parties hereto agree that it would not be just and
equitable if contribution pursuant to this Section 5(d) were determined by PRO
RATA allocation or by any other method of allocation that does not take into
account the equitable considerations referred to in the immediately preceding
paragraph. Notwithstanding the provisions of this Section 5(d), the

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Purchaser shall not be required to contribute,  in the aggregate,  any amount in
excess of the amount by which the proceeds  actually  received by the  Purchaser
from the sale of the Registrable  Securities  subject to the Proceeding  exceeds
the amount of any damages that the Purchaser has otherwise  been required to pay
by reason of such  untrue or alleged  untrue  statement  or  omission or alleged
omission. No Person guilty of fraudulent  misrepresentation  (within the meaning
of Section 11(f) of the Securities Act) shall be entitled to  contribution  from
any Person who was not guilty of such fraudulent misrepresentation.

                  The indemnity and contribution agreements contained in this
Section are in addition to any liability that the Indemnifying Parties may have
to the Indemnified Parties.

         6.       RULE 144

                  The Company shall file the reports required to be filed by it
under the Securities Act and the Exchange Act in a timely manner and, if at any
time the Company is not required to file such reports, they will, upon the
request of any Holder, make publicly available other information so long as
necessary to permit sales of its securities pursuant to Rule 144. The Company
further covenants that it will take such further action as any Holder may
reasonably request, all to the extent required from time to time to enable such
Holder to sell Registrable Securities without registration under the Securities
Act within the limitation of the exemptions provided by Rule 144; PROVIDED,
HOWEVER, that the Company shall not be obligated to provide an opinion to any
Holder regarding the sale of Registrable Securities pursuant to exemptions
provided by Rule 144. Upon the request of any Holder, the Company shall deliver
to such Holder a written certification of a duly authorized officer as to
whether it has complied with such requirements.

         7.       MISCELLANEOUS

                  (a) REMEDIES. In the event of a breach by the Company or by a
Holder, of any of their obligations under this Agreement, each Holder or the
Company, as the case may be, in addition to being entitled to exercise all
rights granted by law and under this Agreement, including recovery of damages,
will be entitled to specific performance of its rights under this Agreement. The
Company and each Holder agree that monetary damages would not provide adequate
compensation for any losses incurred by reason of a breach by it of any of the
provisions of this Agreement and hereby further agrees that, in the event of any
action for specific performance in respect of such breach, it shall waive the
defense that a remedy at law would be adequate.

                  (b) NO INCONSISTENT AGREEMENTS. Neither the Company nor any of
its subsidiaries has, as of the date hereof, nor shall the Company or any of its
subsidiaries, on or after the date of this Agreement, enter into any agreement
with respect to its securities that is inconsistent with the rights granted to
the Holders in this Agreement or otherwise conflicts with the provisions hereof.
Neither the Company nor any of its subsidiaries has previously entered into any
agreement granting any registration rights with respect to any of its securities
to any Person. Without limiting the generality of the foregoing, without the
written consent of the

                                       14
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Holders  of a  majority  of the then  outstanding  Registrable  Securities,  the
Company  shall not grant to any  Person  the right to  request  the  Company  to
register  any  securities  of the Company  under the  Securities  Act unless the
rights so granted are subject in all respects to the prior rights in full of the
Holders set forth herein, and are not otherwise in conflict or inconsistent with
the provisions of this Agreement.

                  (c) NO PIGGYBACK ON REGISTRATIONS. Neither the Company nor any
of its security holders (other than the Holders in such capacity pursuant
hereto) may include securities of the Company in the Registration Statement
other than the Registrable Securities, and the Company shall not enter into any
agreement providing any such right to any of its securityholders.

                  (d) PIGGY-BACK REGISTRATIONS. If at any time when there is not
an effective Registration Statement the Company shall determine to prepare and
file with the Commission a registration statement relating to an offering for
its own account or the account of others under the Securities Act of any of its
equity securities, other than on Form S-4 or Form S-8 (each as promulgated under
the Securities Act) or their then equivalents relating to equity securities to
be issued solely in connection with any acquisition of any entity or business or
equity securities issuable in connection with stock option or other employee
benefit plans, the Company shall send to each holder of Registrable Securities
written notice of such determination and, if within twenty (20) days after
receipt of such notice, any such holder shall so request in writing, the Company
shall include in such registration statement all or any part of the Registrable
Securities such holder requests to be registered. No right to registration of
Registrable Securities under this Section shall be construed to limit any
registration otherwise required hereunder.

                  (e) AMENDMENTS AND WAIVERS. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given, unless the same shall be in writing and signed by the Company
and the Holders of at least a majority of the then outstanding Registrable
Securities; PROVIDED, HOWEVER, that, for the purposes of this sentence,
Registrable Securities that are owned, directly or indirectly, by the Company,
or an Affiliate of the Company are not deemed outstanding. Notwithstanding the
foregoing, a waiver or consent to depart from the provisions hereof with respect
to a matter that relates exclusively to the rights of Holders and that does not
directly or indirectly affect the rights of other Holders may be given by
Holders of at least a majority of the Registrable Securities to which such
waiver or consent relates; PROVIDED, HOWEVER, that the provisions of this
sentence may not be amended, modified, or supplemented except in accordance with
the provisions of the immediately preceding sentence.

                  (f) NOTICES. Any and all notices or other communications or
deliveries required or permitted to be provided hereunder shall be in writing
and shall be deemed given and effective on the earliest of (i) the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile telephone number specified in this Section prior to 8:00 p.m. (New
York City time) on a Business Day, (ii) the Business Day after the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile telephone number specified in the Purchase Agreement later than 8:00
p.m. (New York City

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time) on any date and earlier than 11:59 p.m. (New York City time) on such date,
(iii) the  Business Day  following  the date of mailing,  if sent by  nationally
recognized  overnight courier service,  or (iv) upon actual receipt by the party
to whom such notice is required to be given.

      If to the Company:              PLC Systems Inc.
                                      10 Forge Park
                                      Franklin, MA  02038
                                      Attn:  Chief Executive Officer
                                      Facsimile No.:  (508) 541-7990

      With copies to:                 Mintz, Levin, Cohn, Ferris, Glovsky
                                      and Popeo, P.C.
                                      One Financial Center
                                      Boston, MA  02111
                                      Attn:  Neil H. Aronson
                                      Facsimile No.:  (617) 542-2241

      If to the Southbrook:           Southbrook International Investments, Ltd.
                                      c/o Trippoak Advisors, Inc.
                                      630 Fifth Avenue, Suite 2000
                                      New York, NY 10111
                                      Attn:  Robert L. Miller
                                      Facsimile No.: (212) 332-3256

      If to Brown Simpson LPP         Brown Simpson Strategic Growth Fund, L.P.
                                      152 West 57th Street, 40th Floor
                                      New York, NY 10019
                                      Attn: Mitchell Kaye
                                      Facsimile No.: (212) 247-1329

      If to Brown Simpson LP:         Brown Simpson Strategic
                                      Growth Fund, Ltd.
                                      152 West 57th Street, 40th Floor
                                      New York, NY 10019
                                      Facsimile No.: (212) 247-1329

      of any Purchaser) to:           Robinson Silverman Pearce
                                      Aronsohn & Berman LLP
                                      1290 Avenue of the Americas
                                      New York, NY  10104
                                      Attn:  Kenneth L. Henderson
                                      Fax:  (212) 541-4630

      If to any other Person who is then the registered Holder:

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                  To the address of such Holder as it appears in the stock
                  transfer books of the Company or such other address as may be
                  designated in writing hereafter, in the same manner, by such
                  Person.

                  (g) SUCCESSORS AND ASSIGNS. This Agreement shall inure to the
benefit of and be binding upon the successors and permitted assigns of each of
the parties and shall inure to the benefit of each Holder. The Company may not
assign its rights or obligations hereunder without the prior written consent of
each Holder. The Purchaser may assign its rights hereunder in the manner and to
the Persons as permitted under the Purchase Agreement.

                  (h) ASSIGNMENT OF REGISTRATION RIGHTS. The rights of the
Purchaser hereunder, including the right to have the Company register for resale
Registrable Securities in accordance with the terms of this Agreement, shall be
automatically assignable by the Purchasers to any assignee or transferee of all
or a portion of the Debentures, the Warrants or the Registrable Securities if:
(i) the Purchaser agrees in writing with the transferee or assignee to assign
such rights, and a copy of such agreement is furnished to the Company within a
reasonable time after such assignment, (ii) the Company is, within a reasonable
time after such transfer or assignment, furnished with written notice of (a) the
name and address of such transferee or assignee, and (b) the securities with
respect to such registration rights are being transferred or assigned, (iii)
following such transfer or assignment the further disposition of such securities
by the transferee or assignees restricted under the Securities Act and
applicable state securities laws, (iv) at or before the time the Company
receives the written notice contemplated by clause (ii) of this Section, the
transferee or assignee agrees in writing with the Company to be bound by all of
the provisions of this Agreement, and (v) such transfer shall have been made in
accordance with the applicable requirements of the Purchase Agreement. The
rights to assignment shall apply to the Purchaser's (and to subsequent)
successors and assigns.

                  (i) COUNTERPARTS. This Agreement may be executed in any number
of counterparts, each of which when so executed shall be deemed to be an
original and, all of which taken together shall constitute one and the same
Agreement. In the event that any signature is delivered by facsimile
transmission, such signature shall create a valid binding obligation of the
party executing (or on whose behalf such signature is executed) the same with
the same force and effect as if such facsimile signature were the original
thereof.

                  (j) GOVERNING LAW. This Agreement shall be governed by and
construed in accordance with the laws of the State of New York, without regard
to principles of conflicts of law.

                  (k) CUMULATIVE REMEDIES. The remedies provided herein are
cumulative and not exclusive of any remedies provided by law.

                  (l) SEVERABILITY. If any term, provision, covenant or
restriction of this Agreement is held by a court of competent jurisdiction to be
invalid, illegal, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions set forth herein shall remain in full force and
effect and shall in no way be affected, impaired or invalidated, and the parties
hereto

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shall use their  reasonable  efforts to find and employ an alternative  means to
achieve the same or substantially  the same result as that  contemplated by such
term, provision,  covenant or restriction.  It is hereby stipulated and declared
to be the  intention of the parties that they would have  executed the remaining
terms, provisions, covenants and restrictions without including any of such that
may be hereafter declared invalid, illegal, void or unenforceable.

                  (m) HEADINGS. The headings in this Agreement are for
convenience of reference only and shall not limit or otherwise affect the
meaning hereof.

                  (n) SHARES HELD BY THE COMPANY AND ITS AFFILIATES. Whenever
the consent or approval of Holders of a specified percentage of Registrable
Securities is required hereunder, Registrable Securities held by the Company or
its Affiliates (other than the Purchaser or transferees or successors or assigns
thereof if such Persons are deemed to be Affiliates solely by reason of their
holdings of such Registrable Securities) shall not be counted in determining
whether such consent or approval was given by the Holders of such required
percentage.


                   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK
                            SIGNATURE PAGE TO FOLLOW]

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                  IN WITNESS WHEREOF, the parties have executed this
Registration Rights Agreement as of the date first written above.

                                       PLC SYSTEMS INC.



                                       By:/s/ Patricia L. Murphy
                                          ----------------------
                                              Patricia L. Murphy
                                       Title:Chief Financial Officer


                                       Purchasers:

                                       SOUTHBROOK INTERNATIONAL
                                       INVESTMENTS, LTD.


                                       By:/s/ Kenneth L. Henderson
                                          ------------------------ 
                                              Kenneth L. Henderson
                                              Attorney-in-Fact


                                       BROWN SIMPSON STRATEGIC GROWTH FUND, LTD.


                                       By:/s/ Mitchell Kaye
                                          -----------------
                                              Mitchell Kaye
                                              Principal


                                       BROWN SIMPSON STRATEGIC GROWTH FUND, L.P.



                                       By:/s/ Mitchell Kaye
                                          -----------------
                                              Mitchell Kaye
                                              Principal




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