EXHIBIT 10.1


                           LEASE TERMINATION AGREEMENT

         This Lease Termination Agreement ("Termination Agreement") is entered
into as of March 22, 2004 (the "Effective Date"), by and between BRITANNIA
POINTE GRAND LIMITED PARTNERSHIP, a Delaware limited partnership ("Landlord"),
and VIROLOGIC, INC., a Delaware corporation ("Tenant"), with reference to the
following facts:

                                    RECITALS

         A. Tenant and Landlord are parties to that certain Lease dated August
27, 1997, as amended by a First Amendment to Lease dated as of December 17, 1997
(as amended, the "Lease"), for those certain premises consisting of
approximately 24,725 square feet located on the first and second floors of
Building G in the Britannia Pointe Grand Business Park at 270 East Grand Avenue,
Suite 52, South San Francisco, California (the "Premises").

         B. Concurrently with the execution of this Termination Agreement,
Landlord is entering into a new lease for the Premises with a third party
unaffiliated with Tenant (the "New Lease"). Landlord has advised Tenant that
Landlord will not sign this Termination Agreement until Landlord has received a
signed New Lease from the tenant thereunder.

         C. In connection with the execution of the New Lease, Landlord and
Tenant wish to effect an early termination of the Lease and to release each
other from all further obligations thereunder, effective as of the Effective
Date, subject to the provisions of this Termination Agreement.

         NOW, THEREFORE, in consideration of the foregoing and of the mutual
agreements set forth below, Landlord and Tenant hereby agree as follows:

                                    AGREEMENT

         1. Termination of Lease. Effective as of the Effective Date, the Lease
is terminated and Landlord and Tenant release the other, their respective
predecessors and successors in interest, and their respective affiliates,
officers, directors, partners, shareholders, agents and employees from all past,
present and future covenants, obligations, claims and causes of action, known or
unknown, arising out of or in connection with the Lease, except to the extent
any such matters (a) relate to or arise out of events, circumstances or time
periods occurring prior to the Effective Date (so that, by way of example but
not limitation, the parties will retain their respective rights and obligations
under the Lease with respect to matters such as environmental incidents or
conditions occurring prior to the Effective Date and claims for personal injury
or property damage occurring prior to the Effective Date) or (b) arise under or
are expressly preserved in this Termination Agreement. Nothing in this
Termination Agreement is intended to affect the status or enforceability of any
stock warrants previously issued by Tenant pursuant to or in connection with the
Lease. Tenant shall surrender physical possession of the Premises to Landlord on
the Effective Date in the condition required under this Termination Agreement,
together with all keys and access codes (if any) relating to the Premises.

         2. Termination Payment. Tenant shall pay to Landlord in immediately
available funds, by wire transfer to an account designated in writing by
Landlord, the sum of Four Hundred Thousand and No/100 Dollars ($400,000.00) (the
"Termination Payment") in full satisfaction of all obligations of Tenant under
the Lease (except those obligations, if any, arising under or expressly
preserved in this Termination Agreement). The Termination Payment shall be
payable in two equal installments of Two Hundred Thousand and No/100 Dollars
($200,000.00) each, the first of which installments shall be paid no later than
March 31, 2004 and the second of which installments shall be paid no later than
April 9, 2004.

         3. Condition of Premises. Landlord and Tenant have conducted
walkthroughs and inspections of the Premises and have agreed that there are no
repairs or other actions that must be made, taken or paid for by Tenant in
connection with the surrender of the Premises hereunder; provided, however, that
neither the preceding portion of this sentence nor the release in Paragraph 1
above is intended or shall be construed to waive any of Landlord's rights or
Tenant's obligations under the Lease with respect to any environmental
conditions presently existing in or about the Premises that cannot reasonably be
identified by a walkthrough and visual inspection of the Premises, and Landlord
expressly reserves all of its rights with respect to any such conditions. Tenant
acknowledges that as provided in Section 8.2(c) of the Lease, Tenant waives and
releases any and all rights with respect to any personal property, trade
fixtures or other items remaining on the Premises on the Effective Date.

         4. Security Deposit. Landlord presently holds a security deposit from
Tenant, pursuant to the Lease, in the amount of $11,270.55. Landlord shall
return the security deposit to Tenant within five (5) days after Tenant pays the
second (final) installment of the Termination Payment; provided, however, that
if Tenant has timely paid the required first installment of the Termination
Payment and is making timely payment of the required second installment of the
Termination Payment, then Landlord authorizes Tenant to offset the amount of the
security deposit against the second installment and to make the amount of the
second installment net of that offset.

         5. No Assignment. Each party warrants and represents that it has not
made any assignment, sublease (other than subleases by Tenant that have
previously terminated), transfer, conveyance or other disposition of its
interest in the Lease or of any claim, demand, obligation, liability, action or
cause of action arising out of or in connection with the Lease.

         6. Notices. Any notice or other communication given or required to be
given under this Termination Agreement shall be given in accordance with the
notice provisions set forth in Section 17.1 of the Lease, which provisions are
incorporated herein by this reference as if fully set forth, except that the
parties' respective notice addresses are amended to read as follows:

                  Tenant:           ViroLogic, Inc.
                                    345 Oyster Point Blvd.
                                    South San Francisco, CA  94080
                                    Attn:  Kathy Hibbs, Esq.


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                  with copy to:     Cooley Godward LLP
                                    One Maritime Plaza, 20(th) Floor
                                    San Francisco, CA  94111
                                    Attn:  Kenneth Adelson, Esq.

                  Landlord:         Britannia Pointe Grand Limited Partnership
                                    555 Twelfth Street, Suite 1650
                                    Oakland, CA  94607
                                    Attn:  Magdalena Shushan

                  with copy to:     Slough Estates USA Inc.
                                    444 N. Michigan Avenue, Suite 3230
                                    Chicago, IL  60611
                                    Attn:  Randy Rohner

                  and copy to:      Folger Levin & Kahn LLP
                                    275 Battery Street, 23(rd) Floor
                                    San Francisco, CA  94111
                                    Attn:  Donald E. Kelley, Jr., Esq.

         7. Governing Law. This Termination Agreement shall be governed by and
construed and enforced in accordance with the laws of the State of California,
without giving effect to principles of conflicts of laws.

         8. Counterparts; Facsimile Signatures. This Termination Agreement may
be executed in two or more counterparts, and by separate parties on separate
counterparts, each of which counterparts shall be deemed an original and all of
which counterparts taken together shall constitute one and the same instrument.
The parties contemplate that they may be executing counterparts of this
Agreement transmitted by facsimile, and agree and intend that a signature
delivered by facsimile transmission shall bind the party so signing with the
same effect as though the signature were an original signature.

         9. Broker. Each of Landlord and Tenant respectively represents to the
other that the representing party is not obligated to compensate any broker in
connection with the negotiation or execution of this Termination Agreement.
Landlord and Tenant shall each indemnify and hold the other harmless from and
against any loss, cost, expense or damage arising from any claim for commission
or other compensation made in connection with the negotiation or execution of
this Termination Agreement by any broker claiming by, through or under the
indemnifying party.

         10. Due Authority. Each individual executing this Termination Agreement
on behalf of one of the parties warrants and represents that he or she has the
authority to do so and to bind the legal entity on whose behalf he or she acted.

         11. Waiver of Unknown Claims. Each of Landlord and Tenant respectively,
having been informed of and having read the provisions of California Civil Code
Section 1542, knowingly and intentionally waives any protection afforded to such
party by California Civil Code Section 1542, which provides:


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                  A general release does not extend to claims which the creditor
                  does not know or suspect to exist in his favor at the time of
                  executing the release, which if known by him must have
                  materially affected his settlement with the debtor.

This Termination Agreement is intended to cover all claims or possible claims
arising out of or related to those matters expressly covered by (and not carved
out or reserved from) the releases set forth in this Termination Agreement,
whether such claims or possible claims are known, unknown or hereafter
discovered or ascertained, and the provisions of California Civil Code Section
1542 and any other state and/or Federal counterpart thereto are hereby expressly
waived. Each of Landlord and Tenant respectively expressly acknowledges that it
has been advised by its counsel of the contents and effect of such Section, and
with such knowledge such respective party hereby expressly waives whatever
benefits it may have pursuant to such Section.

         12. Entire Agreement; Amendment. This Termination Agreement contains
the entire agreement of the parties with regard to the subject matter hereof and
there are no other understandings, written or oral, between the parties relating
to the subject matter of this Termination Agreement. No provision of this
Termination Agreement may not be amended or waived except by an agreement in
writing signed by the parties hereto or their respective successors and assigns.

         13. Time of the Essence. Time is of the essence of this Termination
Agreement and of each and every obligation hereunder.

         14. Attorneys' Fees. In the event of any action between the parties
hereto arising out of or in connection with this Termination Agreement, the
prevailing party shall be entitled to recover all reasonable costs, including
(but not limited to) reasonable accountants' fees and attorneys' fees, incurred
by it in connection with such action (including, but not limited to, any
appellate proceedings relating thereto) or in connection with the enforcement of
any judgment rendered in such action. "Prevailing party" within the meaning of
this Section shall include, without limitation, a party who dismisses an action
for recovery hereunder in exchange for payment of the sums allegedly due,
performance of covenants allegedly breached or consideration substantially equal
to the relief sought in the action.

                            [signature page follows]


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         IN WITNESS WHEREOF, the parties have duly executed this Termination
Agreement as of the Effective Date.

LANDLORD:                                           TENANT:


BRITANNIA POINTE GRAND LIMITED                      VIROLOGIC, INC., a Delaware
PARTNERSHIP, a Delaware limited                     corporation
partnership

By:   Britannia Pointe Grand, LLC, a                By:     /s/ William D. Young
      California limited liability                          --------------------
      company, Its General Partner                  Its:    CEO



      By:      /S/ T.J. Bristow                     By:     /s/ Karen Wilson
               -----------------                            -----------------
      Its:     Manager                              Its:    CFO



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