We determined the intrauterine insemination (IUI) pregnancy outcome in the same group of patients when applying different methods of ovulation induction. A group of patients with unexplained (no. 46) and male factor infertility (no. 101) consented to have the following treatment protocol at the American University of Beirut-Infertility Center: IUI to be performed in three natural ovulatory cycles in all patients, then in three clomiphene citrate (CC) stimulated cycles in the remaining non-pregnant patients, and then three cycles with controlled ovarian hyperstimulation (COH) in the remaining group. Of the total 147 patients 130, 138 and 123 underwent 273 natural, 278 CC and 266 COH IUI cycles, respectively. Semen processing for IUI was done by washing the sperm twice and using the swim-up technique. The chi-square test was used for statistical analysis. Pregnancy rate per cycle of IUI with COH (9.8%) was significantly higher than that of IUI in natural cycles (3.3%) but approached significance when compared to IUI with CC cycles (5.4%). Also unexplained infertility cases had a significantly higher pregnancy rate (58.7%) when compared to that of male factor cases (22.8%). IUI still has a place in the treatment of infertility due to selective causes. Combined with COH, IUI gives the best pregnancy rate although its benefit with natural or CC cycles remains obvious.