Clinical results of a combined GnRH-analogue (buserelin, long protocol) + HMG stimulation of 44 IVF-ET or GIFT patients with previously failed pure HMG stimulation have been analysed. The cancellation rate and the incidence of premature LH surge was found to be lower in the buserelin + HMG group than in the control HMG group (30% vs. 40% and 16% vs. 51%). There was no significant difference between the buserelin + HMG and the control HMG group, neither in the number of retrieved and fertilized oocytes and transferred embryos nor in the fertilization and pregnancy rate. The combined GnRH-analogue and gonadotropin therapy led to a decrease of the cancellation rate and of premature LH surge in patients with previously failed pure HMG stimulation. In this group of patients the use of buserelin leads to treatment results comparable to results of pure HMG stimulated patients without previously failed stimulation cycles. Thus the GnRH-analogue + HMG stimulation is recommended for patients with previously unsuccessful pure HMG stimulation.