A variation in the bioactivity of different production lots of human menopausal gonadotropin (hMG) has been suggested. Therefore, we evaluated ovarian response to hMG in 14 women during three separate IVF cycles. The first two cycles were performed with the same lot (#03310027; Cycles A1 and A2); the third cycle utilized different lots of hMG (Cycle B). In all cycles, hMG was administered 3 ampules/day beginning cycle Day 3 and continued for at least 6 days. Estradiol and ultrasound evaluations were performed on Day 3, and then daily, beginning on cycle Day 8. Fourteen women completed all three cycles. There were no significant differences in baseline estradiol and ultrasound. Estradiol levels on Day 8 (A1, 754 +/- 130; A2, 700 +/- 107; B, 520 +/- 80 pg/ml, analysis of variance p greater than 0.5) and on Day 9 (A1, 1051 +/- 144; A2, 1140 +/- 155; B, 840 +/- 124 pg/ml, p greater than 0.05) were similar as well. The number of small (1.0-1.4 cm) follicles, large (greater than or equal to 1.5 cm) follicles, and total follicles (Day 8: total A1, 5.5 +/- 0.9; A2, 4.0 +/- 0.7; B, 4.5 +/- 0.9, p greater than 0.05; Day 9: total A1, 6.7 +/- 0.9; A2, 6.9 +/- 0.8; B, 6.9 +/- 0.9, p greater than 0.05) in all three cycles were also similar.(ABSTRACT TRUNCATED AT 250 WORDS)