EXHIBIT 10f


                          REGISTRATION RIGHTS AGREEMENT
                          -----------------------------


         This  Registration  Rights  Agreement  (this  "Agreement")  is made and
entered  into as of July  17,  1997,  among  PLC  Systems  Inc.,  a  corporation
organized  and  existing  under  the  laws  of  British  Columbia,  Canada  (the
"Company"),  Southbrook International Investments,  Ltd., a corporation existing
under the laws of the British Virgin Islands ("Southbrook"),  HBK Cayman L.P., a
Cayman Islands exempt limited partnership ("HBK Cayman"),  and HBK Offshore Fund
Ltd., a Cayman Islands exempt company ("HBK Offshore").  Southbrook,  HBK Cayman
and HBK Offshore 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.

                  "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.



                                       2


                  "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,  (ii)
exercise  of the  Tranche 1 Warrants  issued by the  Company to the  Purchasers,
(iii) payment of interest in respect of such Tranche 1 Debentures  and (iv) upon
exercise  of common  stock  purchase  warrants  issued by the  Company  to Brown
Simpson,  LLC, (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,  (ii) exercise of the Tranche 2 Warrants  issued by
the Company to the  Purchasers and (iv) payment of interest with respect to such
Debentures;  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,  (2) the  number of shares of Common  Stock  issuable  on payment of
interest on such Debentures during the period after the applicable  Closing Date
and (3) 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)
1,000,000  shares  of  Common  Stock  issuable  upon  conversion  of  Tranche  1
Debentures  and to pay interest in respect of the Tranche 1 Debentures in shares
of Common Stock and (ii) 65,000 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) 145% of the number of shares of Common Stock issuable upon conversion
in full of the  Tranche 2  Debentures  and to pay  interest  in  respect  of the
Tranche 2  Debentures  in shares of Common  Stock 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.




                                       3



                  "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.

                  "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.



                                       4


                  (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  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



                                       5


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  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




                                       6


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.

                  (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


                                       7



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.

                  (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



                                       8


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 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



                                       9


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  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.



                                       10



         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 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 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



                                       11


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 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



                                       12


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 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



                                       13


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 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



                                       14


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 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



                                       15



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 4:30 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 4:30
p.m. (New York City 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



                                       16



         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
                                    Facsimile No.:  (212) 332-3256
                                    Attn:  Robert L. Miller

         If to HBK Cayman:          HBK Cayman L.P.
                                    c/o HBK Investments L.P.
                                    777 Main Street, Suite 2750
                                    Forth Worth, TX  76102
                                    Facsimile No.:  (817) 870-6234
                                    Attn:  David C. Haley and Michael Reese

         If to HBK Offshore:        HBK Offshore Fund Ltd.
                                    c/o HBK Investments L.P.
                                    777 Main Street, Suite 2750
                                    Forth Worth, TX  76102
                                    Facsimile No.:  (817) 870-6234
                                    Attn:  David C. Haley and Michael Reese

         With copies in the case of
         Southbrook, HBK Cayman, and
         HBK Offshore to:           Robinson Silverman Pearce
                                      Aronsohn & Berman LLP
                                    1290 Avenue of the Americas
                                    New York, NY  10104
                                    Attn:  Eric L. Cohen
                                    Fax:  (212) 541-4630

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

                                    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.



                                       17


                  (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  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



                                       18


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]




                                       19




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

                                    PLC SYSTEMS INC.



                                    By:________________________
                                        Name:
                                        Title:


                   SOUTHBROOK INTERNATIONAL INVESTMENTS, LTD.



                                    By:________________________
                                        Name:
                                        Title:


                                    HBK CAYMAN L.P.



                                    By:________________________
                                        Name:
                                        Title:


                                    HBK OFFSHORE FUND LTD.



                                    By:________________________
                                        Name:
                                        Title:


                                       20