SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                              (Amendment No. ___)*


                               ThermoGenesis Corp.
                                (Name of Issuer)


                         Common Stock, $0.001 Par Value
                         (Title of Class of Securities)


                                   883623 209
                                 (CUSIP Number)


Check the  appropriate box to designate the rule pursuant to which this Schedule
is filed:

|_|  Rule 13d-1(b)
|X|  Rule 13d-1(c)
|_|  Rule 13d-1(d)

*The  remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).

2

CUSIP No.    883623 209

- -------------------------------------------------------------------------------
1.      NAME OF REPORTING PERSON                                 ATLAS II,  L.P.
        S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
- -------------------------------------------------------------------------------
2.      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                       a |_|
                                                                       b |_|
- -------------------------------------------------------------------------------
3.      SEC USE ONLY
- -------------------------------------------------------------------------------
4.      CITIZENSHIP OR PLACE OF ORGANIZATION

                New York
- -------------------------------------------------------------------------------

                                          5. SOLE VOTING POWER

                   NUMBER OF                       2,427,910
                    SHARES
                 BENEFICIALLY             --------------------------------------
                     OWNED                6. SHARED VOTING POWER
                    BY EACH
                   REPORTING                               0
                  PERSON WITH             --------------------------------------
                                          7. SOLE DISPOSITIVE POWER

                                                   2,427,910
                                          --------------------------------------
                                          8. SHARED DISPOSITIVE POWER

                                                           0
- --------------------------------------------------------------------------------


9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

             2,427,910
- --------------------------------------------------------------------------------
10.     CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*  |_|

- --------------------------------------------------------------------------------
11.     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                   7.7%
- --------------------------------------------------------------------------------
12.     TYPE OF REPORTING PERSON*

                    PN
- --------------------------------------------------------------------------------

3

                                  SCHEDULE 13G

Item 1. Name and Address of Issuer

     (a)  THERMOGENESIS CORP.

     (b)  3146 Gold Camp Drive
          Rancho Cordova, CA 95670

Item 2. Name, Address and Citizenship of Person Filing;  Class of Securities and
        CUSIP Number

     (a)  Atlas II, L.P.

     (b)  630 Fifth Avenue, 20th Floor
          New York, NY 10100

     (c)  USA

     (d)  Common Stock

     (e)  883623 209

Item 3. If this statement is filed pursuant to Rule 13d-1(b), or 13d-2(b), check
        whether the person filing is a:

(a)  |_| Broker or Dealer registered under Section 15 of the Act

(b)  |_| Bank is defined in Section 3(a)(6) of the Act

(c)  |_| Insurance Company as defined in Section 3(a)(19) of the Act

(d)  |_| Investment Company registered under Section 8 of the Investment Company
         Act

(e)  |_| Investment  Adviser  registered  under  Section 203 of the  Investment
         Advisers Act of 1940

(f)  |_| Employee Benefit Plan,  Pension Fund which is subject to the provisions
         of the Employee  Retirement  Income Security Act of 1974 or Endowment
         Fund; see ss.240.13d-1(b)(1)(ii)(F)

(g)  |_| Parent Holding Company, in accordance withss.240.13d-1(b)(ii)(G)
         (Note: See Item 7)

4

(h)  |_| Group, in accordance withss.240.13d-1(b)(1)(ii)(H)

Item 4. Ownership

     (a)  Amount Beneficially Owned: 2,427,910 (1)

     (b)  Percent of Class: 7.7%

     (c)  Number of shares as to which such person has:

          (i)  sole power to vote or to direct the vote:            2,427,910(1)
         (ii)  shared power to vote or to direct the vote:                  0
        (iii)  sole  power  to  dispose  or  to  direct the
               disposition of:                                        427,910(1)
         (iv)  shared power to dispose or to direct the
               disposition of:                                              0
- --------------------


(1)  1,844,425 shares of Common Stock and warrants to purchase 583,485 shares of
     Common Stock exercisable within 60 days
- -------------------------------------------------------------------------------
Item 5. Ownership of Five Percent or Less of a Class

          If this  Statement  is being  filed to report  the fact that as of the
          date hereof the reporting person has ceased to be the beneficial owner
          of more  than  five  percent  of the  class of  securities,  check the
          following:       |_|.
- -------------------------------------------------------------------------------
Item 6. Ownership of More than Five Percent on Behalf of Another Person

          Not applicable.
- -------------------------------------------------------------------------------
Item 7. Identification and Classification of the Subsidiary which Acquired the
        Security Being Reported on by the Parent Holding Company

          Not applicable
- -------------------------------------------------------------------------------
Item 8. Identification and Classification of Members of the Group

               Not applicable.
- -------------------------------------------------------------------------------
Item 9. Notice of Dissolution of Group

               Not applicable.

5


Item 10. Certification

     By signing  below,  I certify that, to the best of my knowledge and belief,
the  securities  referred  to above were not  acquired  and are not held for the
purpose of or with the effect of  changing  or  influencing  the  control of the
issuer of the  securities  and were not acquired and are not held in  connection
with or as a participant in any transactions having that purposes or effect.

                                    Signature

     After  reasonable  inquiry and to the best of my  knowledge  and belief,  I
certify that the information  set forth in this statement is true,  complete and
correct.


Date:  May 3, 2001                                     ATLAS II, L.P.


                                             /s/   RICHARD JACINTO
                                                   ----------------------------
                                                   Richard Jacinto
                                                   General Partner