Intrauterine insemination (IUI) has been used for the treatment of various causes of infertility, including unexplained infertility, male factor, and cervical factor. Some centers frequently use superovulation combined with IUI. The study presented herein attempted to evaluate the efficacy of IUI without superovulation in cases where all causes of infertility other than cervical or male factors have been eliminated. However, in the case of poor or absent cervical mucus, the use of controlled ovarian hyperstimulation (COH) may obscure the actual importance of the IUI, since it is possible that the poor cervical mucus is related to poor timing, inadequate follicular maturation, or low estradiol levels, which if corrected will obviate the need for IUI. In this study IUI was targeted for 36-40 h following the sera luteinizing hormone surge. A total of 108 patients were enrolled in this study: 47 with male factor, 61 with cervical factor. Patients were followed for a maximum of three cycles unless a pregnancy occurred within 3 months of treatment. Comparison of pregnancy rates (PRs) were based on diagnosis. The cumulative PRs per cycle for each of the three cycles studied were as follows: cervical factor--19.7, 36.8, and 36.8%; male factor--12.8, 29.3, and 38.3%. Thus, PRs were comparable for both groups after three treatment cycles. These data demonstrate that IUI is an effective therapy for cervical and/or male factor, even without superovulation.