<PAGE>

                                                                    EXHIBIT 99.3

                               US ONCOLOGY, INC.

                         NOTICE OF GUARANTEED DELIVERY

  This form or one substantially equivalent to this form must be used to accept
the offer (the "Exchange Offer") of US Oncology, Inc. to exchange an aggregate
principal amount of up to $175,000,000 of its 9 5/8% Senior Subordinated Notes
due 2012 (the "New Notes"), the issuance of which has been registered under the
Securities Act of 1933, as amended (the "Securities Act"), for a like principal
amount of its issued and outstanding 9 5/8% Senior Subordinated Notes due 2012
(the "Old Notes"), which were issued in offerings under Rule 144A and
Regulation S of the Securities Act that were not registered under the
Securities Act. The Exchange Offer will expire at 5:00 p.m., New York City
time, on         , 2002, unless extended (as it may be extended, the
"Expiration Date"). As described in the enclosed Prospectus, dated       , 2002
(the "Prospectus"), if you are a registered holder of Old Notes and wish to
tender your Old Notes, but (1) the certificates for Old Notes are not
immediately available, (2) time will not permit your certificates for Old Notes
or other required documents to reach JPMorgan Chase Bank, as exchange agent
(the "Exchange Agent"), before the Expiration Date or (3) the procedure for
book-entry transfer cannot be completed before the Expiration Date, you may
effect a tender of your Old Notes if (1) the tender is made through an Eligible
Guarantor Institution (as defined in the Prospectus under the caption "The
exchange offer--Procedures for tendering old notes"); (2) prior to the
Expiration Date, the Exchange Agent receives from an Eligible Guarantor
Institution a properly completed and duly executed Notice of Guaranteed
Delivery, substantially in this form, setting forth your name and address, and
the amount of Old Notes you are tendering and stating that the tender is being
made by Notice of Guaranteed Delivery. These documents may be sent by overnight
courier, registered or certified mail or facsimile transmission. If you elect
to use this procedure, you must also guarantee that within three New York Stock
Exchange, Inc. ("NYSE") trading days after the date of execution of the Notice
of Guaranteed Delivery, the certificates for all physically tendered Old Notes,
in proper form for transfer, or a confirmation of book-entry transfer (a "Book-
Entry Confirmation") of the Old Notes into the Exchange Agent's account at The
Depository Trust Company in accordance with The Depository Trust Company's
Automated Tender Offer Program, as the case may be, a properly completed and
duly executed Letter of Transmittal, with any required signature guarantees,
and all other documents required by the Letter of Transmittal, or, in the case
of Book-Entry Confirmation, a properly completed and duly executed Letter of
Transmittal, with any required signature guarantees, or an Agent's Message (as
defined in the Prospectus under the caption "The exchange offer--Procedures for
tendering old notes") instead of the Letter of Transmittal, will be deposited
by the Eligible Guarantor Institution with the Exchange Agent; and (3) the
Exchange Agent receives the certificates for all physically tendered Old Notes,
in proper form for transfer, or a Book-Entry Confirmation of transfer of the
Old Notes into the Exchange Agent's account at The Depository Trust Company in
accordance with The Depository Trust Company's Automated Tender Offer Program,
as the case may be, a properly completed and duly executed letter of
transmittal, with any required signature guarantees, and all other required
documents or, in the case of a Book-Entry Confirmation, a properly completed
and duly executed Letter of Transmittal, with any required signature
guarantees, or an Agent's Message instead of the Letter of Transmittal, in each
case, within three NYSE trading days after the date of execution of this Notice
of Guaranteed Delivery.

                Delivery to: JPMorgan Chase Bank, Exchange Agent

<TABLE>
<S>                           <C>                           <C>
   By Regular or Certified
            Mail:                     By Facsimile:         By Overnight Courier or Hand:
                         (Eligible Guarantor Institutions Only)

     JPMorgan Chase Bank           JPMorgan Chase Bank           JPMorgan Chase Bank
   Attention: Frank Ivins        Attention: Frank Ivins        Attention: Frank Ivins
   2001 Bryan Street, 10th
            Floor             2001 Bryan Street, 10th Floor 2001 Bryan Street, 10th Floor
     Dallas, Texas 75201           Dallas, Texas 75201           Dallas, Texas 75201
                                   Fax: (214) 468-6092

                                 To Confirm by Telephone
                                or for Information Call:

                                   JPMorgan Chase Bank
                                 Attention: Frank Ivins
                              2001 Bryan Street, 10th Floor
                                   Dallas, Texas 75201
                                  Phone: (214) 468-6464
</TABLE>

  Delivery of a Letter of Transmittal or Agent's Message to an address other
than the address listed above or transmission of instructions by facsimile
other than as set forth above is not valid delivery of the Letter of
Transmittal or Agent's Message.
<PAGE>

Ladies and Gentlemen:

  Subject to the terms and conditions set forth in the Prospectus and the
accompanying Letter of Transmittal, the undersigned hereby tenders to US
Oncology, Inc. the principal amount of Old Notes set forth below pursuant to
the guaranteed delivery procedure described in the Prospectus under the caption
"The exchange offer--Guaranteed delivery procedures."


<TABLE>
  <S>                           <C>                           <C>
   Certificate Nos. (if known)
             of Old
   Notes or Account No. at The       Aggregate Principal           Aggregate Principal
    Depository Trust Company         Amount Represented             Amount Tendered*
</TABLE>

--------------------------------------------------------------------------------




 * Must be in denominations of principal amount of $1,000 and any integral
 multiple thereof.

--------------------------------------------------------------------------------
  All authority herein conferred or agreed to be conferred shall survive the
death or incapacity of the undersigned and every obligation of the undersigned
hereunder shall be binding upon the heirs, personal representatives, successors
and assigns of the undersigned.

--------------------------------------------------------------------------------

                                PLEASE SIGN HERE

 X ___________________________________    ___________________________________


 X ___________________________________    ___________________________________

       Signature(s) of Owner(s)                           Date
        or Authorized Signatory

          Area Code and Telephone Number: (   )    -


  Must be signed by the holder(s) of Old Notes as their name(s) appear(s) on
certificates for Old Notes or on a security position listing, or by person(s)
authorized to become registered holder(s) by endorsement and documents
transmitted with this Notice of Guaranteed Delivery. If signature is by a
trustee, executor, administrator, guardian, attorney-in-fact, officer or other
person acting in a fiduciary or representative capacity, such person must set
forth his or her full title below.

                                       2
<PAGE>

                      Please print name(s) and address(es)

Name(s): _______________________________________________________________________

    ------------------------------------------------------------------------

    ------------------------------------------------------------------------

Capacity:_______________________________________________________________________

Address(es):____________________________________________________________________

     -----------------------------------------------------------------------

     -----------------------------------------------------------------------

                                   GUARANTEE

                    (Not to be used for signature guarantee)

  The undersigned, an Eligible Guarantor Institution, hereby guarantees that
the certificates representing the principal amount of Old Notes tendered hereby
in proper form for transfer, or timely confirmation of the book-entry transfer
of such Old Notes into the Exchange Agent's account at The Depository Trust
Company pursuant to the procedures set forth in the Prospectus under the
caption "The exchange offer--Guaranteed delivery procedures," together with any
required signature guarantee and any other documents required by the Letter of
Transmittal, will be received by the Exchange Agent at the address set forth
above, no later than three NYSE trading days after the Expiration Date.

------------------------------------     ------------------------------------
            Name of Firm

                                                 Authorized Signature

------------------------------------     ------------------------------------
              Address

                                                        Title

------------------------------------
              Zip Code                   Name: ______________________________

                                                    (Please Type or Print)

Area Code and Telephone Number:          Dated: _________________________, 2002


NOTE: DO NOT SEND CERTIFICATES FOR OLD NOTES WITH THIS FORM. CERTIFICATES FOR
      OLD NOTES SHOULD BE SENT ONLY WITH A COPY OF YOUR PREVIOUSLY EXECUTED
      LETTER OF TRANSMITTAL.

                                       3