Exhibit 10.10


                          FULL RECOURSE PROMISSORY NOTE

                                                                  June 23, 2000

$299,999.38

         FOR VALUE RECEIVED, Don M. Hardison (the "Maker") promises to pay to
the order of Exact Laboratories a Delaware corporation (the "Holder"), having an
address at 63 Great Road, Maynard, Massachusetts 01754, or its assigns, the
principal sum of $299,999.38, together with interest on the principal of this
Note outstanding at the rate of 9.5% per year. All principal and accrued
interest shall be paid on, or prior to, ten years from the date hereof.

         Interest on this Note shall be computed on the basis of a year of 365
days for the actual number of days elapsed. All payments by the Maker under this
Note shall be in immediately available funds.

         Every amount overdue under this Note shall bear interest from and after
the date on which such amount first became overdue at an annual rate which is
two (2) percentage points above the rate per year specified in the first
paragraph of this Note. Such interest on overdue amounts under this Note shall
be payable on demand and shall accrue and be compounded monthly until the
obligation of the Maker with respect to the payment of such interest has been
discharged (whether before or after judgment).

         In no event shall any interest charged, collected or reserved under
this Note exceed the maximum rate then permitted by applicable law.

         All payments by the Maker under this Note shall be made without
set-off, defense or counterclaim and be free and clear and without any deduction
or withholding for any taxes or fees of any nature whatever, unless the
obligation to make such deduction or withholding is imposed by law.

         Maker agrees that: (i) upon the failure to pay when due the principal
balance and accrued interest hereunder; (ii) if Maker (1) commences any
voluntary proceeding under any provision of Title 11 of the United States Code,
as now or hereafter amended, or commences any other proceeding, under any law,
now or hereafter in force, relating to bankruptcy, insolvency, reorganization,
liquidation, or otherwise to the relief of debtors or the readjustment of
indebtedness, (2) makes any assignment for the benefit of creditors or a
composition or similar arrangement with such creditors, or (3) appoints a
receiver, trustee or similar judicial officer or agent to take charge of or
liquidate any of its property or assets; or (iii) upon the commencement against
Maker of any involuntary proceeding of the kind described in paragraph (ii),
principal and accrued interest under this Note shall become immediately due and
payable without presentment, demand, protest or notice of any kind.

         The Maker shall remain personally liable to the Holder with respect to
all of the obligations under this Note and the Holder shall have full recourse
against Maker.


                                      -2-

         No delay or omission on the part of the Holder in exercising any right
under this Note shall operate as a waiver of such right or of any other right of
the Holder, nor shall any delay, omission or waiver on any one occasion be
deemed a bar to or waiver of the same or any other right on any future occasion.

         None of the terms or provisions of this Note may be excluded, modified
or amended except by a written instrument duly executed by the Holder and the
Maker expressly referring to this Note and setting forth the provision so
excluded, modified or amended.

         Maker hereby forever waives presentment, demand, presentment for
payment, protest, notice of protest, notice of dishonor of this Note and all
other demands and notices in connection with the delivery, acceptance,
performance and enforcement of this Note.

         This Note shall be governed and construed in accordance with the laws
of the Commonwealth of Massachusetts applicable to agreements made and performed
entirely in such State, without regard to conflict of laws principles thereof,
and shall be binding upon the successors or assigns of the Maker and shall inure
to the benefit of the successors and assigns of the Holder.


                                                         /s/ Don M. Hardison
                                                         ----------------------
                                                         Don M. Hardison