Forty-eight patients with male (n = 16) or idiopathic (n = 32) infertility were stimulated with human menopausal gonadotropin. Intrauterine insemination (IUI) or natural intercourse were performed after either human chorionic gonadotropin (hCG)-induced or spontaneous, urinary luteinizing hormone (LH) surge-monitored ovulation. A total of 148 cycles were analyzed. In 40 cycles treated with hCG-induced ovulation and IUI, 3 (7.5%) patients conceived, whereas 37 women accomplished natural intercourse after hCG-induced ovulation and 2 (5.5%) became pregnant. When inseminated after a spontaneous LH surge, 3 (8.8%) of 34 patients achieved a pregnancy; no conception occurred in 37 spontaneously ovulatory cycles combined with timed intercourse. Pregnancy rates did not substantially differ between the treatment modalities or between mono-ovulatory and polyovulatory cycles. The cycle characteristics between spontaneous ovulatory and hCG-induced cycles significantly did differ.