To evaluate the effectiveness of intrauterine insemination (IUI) in the treatment of infertility, timed-intercourse and intrauterine insemination by husband in stimulated cycles with clomiphene citrate and gonadotropins were compared in a total of 105 cycles. Patients received 100 mg of clomiphene citrate daily for 5 days starting on day 3 of the menstrual cycle followed by hMG or FSH. Doses of exogenous gonadotropins were adjusted by the follicular development and concentrations of serum estradiol (E2). More than 3 follicles reaching >16 mm were present in the ovary, 5,000 IU of hCG was administered intramusculary. Patients received a maximum of three intercourse or IUI cycles for the treatment. Severe male (<10x106 motile sperm) or age factor (>39 y) patients were excluded in this study. Pregnancy was classified as clinical if a gestational sac or fetal cardiac activity was seen on ultrasound. The overall clinical pregnancy rates were 17.1% per cycle (18/105) and 21.2% per patient (18/85). The pregnancy rates (per cycle) were 17.5% (l1/63) in intercourse and 16.7% (7/42) in IUI groups, respectively. IUI had no significant improvement in pregnancy rate compared with timed-intercourse. The multiple pregnancy rates were 11.1% (1 twin and 1 triplet). No patient developed ovarian hyperstimulation. Abortion rate was 28.6% (2/7) in IUI group only. The delivery and ongoing pregnancy rates were 15.2% per cycle (16/105) and 18.8% per patient (16/85). There were no differences in age, duration of infertility, follicle size and level of estradiol (E2) on the day of hCG injection in pregnant and non-pregnant groups. However, total doses of gonadotropins were higher in pregnant group than in non-pregnant group (p<0.01). Pregnancy rate was not affected by ovulatory status at the time of insemination. These results indicate that well timed-intercourse in stimulated cycles is as effective as IUI for infertile couples.