Fecundity rates were measured for 343 patients in 467 cycles of ovulation induction with intrauterine insemination (IUI) from January 1990 to April 1992. Total pregnancy rate per cycle (PR) was 15.6% with a spontaneous abortion (SA) rate of 19.2%, an ectopic pregnancy (EP) rate of 4.1%, a multiple pregnancy (MP) rate of 19.2%, and an ongoing or live-birth (LB) rate of 12.0%. Using gonadotropins as a unique or as an additional stimulatory reagent improved the pregnancy rate of anovulatory patients by more than three-fold over use of clomiphene citrate (CC) alone (33.3% vs 10.7%). In other diagnostic entities, the PRs were higher, but the difference was not statistically significant between these two stimulation protocols (13.9% vs 8.4%; t = 1.70, p > 0.05). Pretreatment sperm motility and the post-treatment total motile sperm count were significantly correlated with the PRs. The same phenomena occurred when the number of follicles > or = 12 mm and the serum estradiol concentrations were taken into account. The highest PR was detected when the endometrial thickness fell between 8 and 13 mm. The spontaneous abortion rate was higher in CC only cycles and when the serum E2 was below 1000 pg/mL on the day human chorionic gonadotropin was administered. A multiple pregnancy could be predicted when a cycle of more than 10 follicles > or = 12 mm was detected (44.4%). The complications of controlled ovarian hyperstimulation with IUI were low and mild in our study, comprising six cases of moderate to severe ovarian hyperstimulation syndrome and three cases of acute pelvic inflammatory disease.(ABSTRACT TRUNCATED AT 250 WORDS)