EXHIBIT 99.6

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO SECTION
                     906 OF THE SARBANES-OXLEY ACT OF 2002

         In connection with the Annual Report of YM BioSciences Inc. (the
"Company") on Form 40-F for the year ended June 30, 2004, as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, David
G.P. Allan, Chief Executive Officer of the Company, certify, pursuant to 18
U.S.C. section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, that to the best of my knowledge:

1.    The Report fully complies with the requirements of section 13(a) or 15(d)
      of the Securities Exchange Act of 1934; and

2.    The information contained in the Report fairly presents, in all material
      respects, the financial condition and results of operations of the
      Company.

      By:  /s/ David G.P. Allan
           -------------------------------------------
           David G.P. Allan
           Chief Executive Officer
           (Principal Executive Officer)

November 12, 2004