['Leuprolide acetate (LA) has improved the efficiency of human menopausal gonadotropins (hMG) in in vitro fertilization cycles. We hypothesized that the combination of LA/hMG/intrauterine insemination (IUI) would be more efficacious than hMG/IUI cycles.', 'During an 18-month period, all patients completing either a hMG/IUI cycle (group I) or a LA/hMG/IUI cycle (group II) had the characteristics and outcomes of their stimulation cycles assessed. The groups were not prospectively randomized.', 'Referral center at a tertiary care hospital.', 'One hundred twenty three patients in group I completed 219 cycles, and 64 patients in group II completed 102 cycles. Twenty-eight of the patients who failed to conceive with hMG/IUI were advanced to group II.', 'Pregnancy/IUI is compared between the two groups.', 'Group II demonstrated significantly greater clinical pregnancy/IUI than group I (26.5% and 16.0%, respectively, P less than 0.05), as well as a higher live birth/IUI (21.6% and 12.8%, respectively, P less than 0.05). No difference was present in the rate of fetal wastage or multiple births.'] Does gonadotropin-releasing hormone agonist improve the efficiency of controlled ovarian hyperstimulation/intrauterine insemination?