EXHIBIT 10.18

                                    SUBLEASE

         THIS SUBLEASE (the "Sublease") is made as of the 29th day of September,
1998,  between  HEALTHDESK  CORPORATION,  a California  corporation,  having its
principal  place  of  business  at  2560  Ninth  Street,  Suite  220,  Berkeley,
California 94710  ("Sublandlord") and PATIENT  INFOSYSTEMS  ACQUISITION CORP., a
Delaware  corporation,  having  its  principal  place of  business  at 46 Prince
Street, Rochester, New York 14607 ("Subtenant").

                                    RECITALS:

         A.  Sublandlord  is tenant under an Office Lease (the "Prime  Lease," a
complete copy of which is annexed hereto as Schedule A) dated September 11, 1995
with Parker Associates,  a California limited  partnership (the "Prime Lessor"),
relating to property identified as Suite 220 in Parker Plaza, 2560 Ninth Street,
Berkeley,  California,  more  particularly  described  in the Prime  Lease,  and
referred to herein as the "Premises."

         B. Sublandlord desires to sublet to Subtenant, and Subtenant desires to
sublet from Sublandlord, all of the Premises.

         NOW,  THEREFORE,  for good and valuable  consideration,  the receipt of
which is hereby acknowledged, the parties hereby agree:

         1........Sublease.   Sublandlord   hereby  subleases  the  Premises  to
Subtenant, and Subtenant hereby subleases the Premises from Sublandlord,  on the
terms and conditions hereinafter set forth.

         2........Term  of  Sublease.  The Sublease  shall  commence on the date
hereof  (the  "Commencement  Date")  and  shall  be  a  month-to-month   tenancy
terminable upon 10 business days advance written notice by either party.

         3........Rent.  Subtenant  shall pay Sublandlord the Rent at the office
of Sublandlord first above appearing,  or at such other place as Sublandlord may
designate in writing.  Rent shall be payable in equal  monthly  installments  in
advance on the first day of each calendar month during the Term.

         4........Occupancy. Subject to the terms and provisions hereinafter set
forth,  Subtenant  shall be permitted to enter into occupancy of the Premises on
the Commencement Date.

         5........Prime Lease; Inapplicable Provisions. This Sublease is subject
to and subordinate to the Prime Lease, and all defined terms used herein, unless
otherwise  indicated,  shall have the meanings given to them in the Prime Lease.
The term  "Landlord"  as used in the  Prime  Lease  shall  refer to  Sublandlord
hereunder,  "Tenant"  as  used in the  Prime  Lease  shall  refer  to  Subtenant
hereunder,  "Commencement  Date"  shall refer to the  Commencement  Date of this
Sublease  and  "Term"  shall  refer  to the  Term of this  Sublease,  except  as
otherwise expressly provided in this Sublease. The obligations of Sublandlord in
the Prime Lease shall be the obligations of Subtenant  hereunder,  and Subtenant
assumes and shall perform all of the terms of the Prime Lease to be performed by
Sublandlord  as tenant  thereunder  with respect to the Premises for the term of
this  Sublease,  except to the  extent  the  provisions  of the Prime  Lease are
inconsistent  with or are  superseded  or  supplemented  by  specific  terms and
provisions of this Sublease.  The following  provisions of the Prime Lease shall
not apply to this Sublease:

         .........(a)  The Term (paragraph 3(a));

         .........(b)  Security Deposit (paragraph 15);

         .........(c)  Rental Adjustment (paragraph 29);

         .........(d)  Taxes Payable by Tenant (paragraph 30); and

         .........(e)  Basic Operating Costs (Paragraph 38).

         6.  Prime  Lease  Indemnity.  Subtenant  shall  neither  do nor  permit
anything  to be done  which  would  cause the Prime  Lease to be  terminated  or
forfeited by reason of any right of termination or forfeiture reserved or vested
in the Prime Lessor under the Prime Lease,  and  Subtenant  shall  indemnify and
hold Sublandlord  harmless from and against all claims of any kind whatsoever by
reason of any breach or default on the part of  Subtenant by reason of which the
Prime Lease may be terminated or forfeited.

         7. "As Is" Condition.  Subtenant has inspected the Premises and accepts
the  same  from  Sublandlord  in  its  present   condition  "as  is."  Subtenant
acknowledges  and agrees with  Sublandlord  that  neither  Sublandlord,  nor any
employee of Sublandlord, nor other party claiming to act on Sublandlord's behalf
has made any  representation,  warranty,  estimation,  or promise of any kind or
nature whatsoever relating to the physical condition of the Premises.

         8. Prime Lessor Consent.  The Sublease shall be of no force and effect,
and the parties shall have no rights or liabilities  hereunder,  until the terms
hereof are approved in writing by Prime Lessor.  Either party can terminate this
Sublease if the  contingency  in the prior  sentence  has not been  satisfied or
waived by September 30, 1998.

         9........Miscellaneous.

         .........(a)  Each party warrants that it is authorized to enter into 
the Sublease, that the person signing on its behalf is duly authorized to
execute the Sublease, and that no other signatures are necessary.

     .........(b) All prior  understandings  and agreements  between the parties
with respect to the subject matter hereof are merged within this Sublease, which
alone fully and completely  sets forth the  understanding  of the parties.  This
Sublease  shall  not be  modified,  altered  or  amended  in any way  except  by
agreement in writing, signed by the parties hereto.

     .........(c) The terms, covenants and conditions contained in this Sublease
shall be binding on and inure to the  benefit  of the  parties  hereto and their
respective permitted successors and permitted assigns.

     .........(d)  If any provision of the Sublease is invalid or  unenforceable
to any extent,  then that  provision and the  remainder of this  Sublease  shall
continue in effect and be enforceable to the fullest extent permitted by law.

     .........(e) The parties chose this Sublease document because it is fair to
both parties. Therefore, the parties agree that it shall be construed as if both
parties  were  equally  responsible  for  drafting  the Sublease and the rule of
construction of construing against the drafter shall not apply.

     .........(f)  This  Sublease  shall be governed by the laws of the State of
California.
     .........(g)  This  Sublease  shall not be  binding  unless  signed by both
parties and an originally signed counterpart is delivered to Subtenant.

     .........(h)  Subtenant  warrants and represents to  Sublandlord  that this
Sublease  and the  transaction  contemplated  hereby is legally  binding on, and
enforceable against Subtenant in accordance with its terms.

     .........(i)  Notices  shall  be sent  and  deemed  to have  been  given as
provided in Paragraph 28 of the Prime Lease,  to  Sublandlord  and  Subtenant at
their addresses in the first paragraph of this Sublease.

<PAGE>



         INTENDING TO BE LEGALLY BOUND,  this instrument has been executed as of
the day and year first appearing.

         .........                                SUBLANDLORD:

         .........                                EALTHDESK CORPORATION



         .........                                By: /s/  Terry M. Brandt
                                                      --------------------
         .........                                Name:  Terry M. Brandt
         .........                                Title: Chief Technical Officer
  
         .........                                SUBTENANT:

         .........                                PATIENT INFOSYSTEMS
         .........                                ACQUISITION CORP.



         .........                                 By:  /s/  Donald A. Carlberg
                                                        ----------------------
         .........                                 Name:  Donald A. Carlberg
         .........                                 Title:    President