Eighty-eight IVF-ET cycles were classified into four groups according to the results of IVF-ET (Group A-conceptional cycles, 10 cycles; Group B-cycles with cleaved oocytes, 58 cycles; Group C-cycles with fertilized oocytes, 9 cycles; Group D-cycles without fertilization, 11 cycles). Serum luteinizing hormone (LH), estradiol (E2), and progesterone (P) levels during follicle stimulation were studied in these groups. Patients participated in our IVF-ET program due to irreparable tubal damage. Follicle development was stimulated with a clomiphene-human menopausal gonadotropin (hMG)-human chorionic gonadotropin (hCG) regimen. Group C showed a low E2 response to follicle stimulation. Groups B and D showed significantly higher serum P levels on day 0 (the day of hCG injection) than Group A (Group A, 0.73 +/- 0.11, vs Groups B and D, 1.43 +/- 0.15 and 2.17 +/- 0.42 ng/ml; P less than 0.01). The effects of serum P and LH levels on the fertilization and pregnancy rates were studied. The pregnancy rate was not affected by the serum LH level but was only 2.7% in cycles in which serum P was 1.2 ng/ml on day 0, which was significantly lower than that in cycles in which serum P was less than 1.2 ng/ml on day 0 (19.1%) (P less than 0.05). The fertilization rate was significantly lower in the cycles with higher levels of serum P and/or LH than in cycles in which serum P was less than 1.2 ng/ml and serum LH was normal (50.5 vs 78.8%; P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)