This study was conducted to compare pregnancy rates following two different timings of intrauterine insemination (IUI) in ovarian stimulated cycles. This retrospective study included 135 couples undergoing treatment for infertility. IUI was performed at either 24 hr or 36 hr after hCG injection. Pregnancy rates did not differ between the two groups or in subgroups receiving different methods of ovarian stimulation. Pregnancy rates were similar when IUI was performed at either 24 or 36 hr after hCG injection in ovarian stimulated cycles.