Background: Intrauterine insemination (IUI) combined with controlledovarian hyperstimulation (COH) has been demonstrated to be an effective form of treatment for subfertile couples.Objective: To determine the optimal timing of IUI in relation to hCGadministration with different protocols of induction ovulation.Design: Prospective randomized study.Setting: Infertility Clinic, Department of Obstetrics and Gynecology-Cairo University Hospitals-, Kasr El Aini.Patients and Methods: Forty-five patients with mild male factor andunexplained infertility. After COH with clomiphene citrate (CC) orgonadotrophins (hMG), patients were randomly assigned to one of thefollowing groups: group 1 received IUI 24 hours after hCG administration,group 2 received IUI 32 hours after hCG administration and group 3 received IUI 40 hours after hCG administration.Outcome: Number of dominant follicles and endometrial thickness on theday of hCG administration and pregnancy rates.Results: Forty-five patients underwent 125 IUI cycles: 15 patients weretreated for 42 cycles in group 1, 15 patients for 41 cycles in group 2, and 15patients for 42 cycles in group 3. The overall pregnancy rates per cycle forgroups 1, 2, and 3 were 14.3%, 17% and 21.4% respectively. There was nostatistical significant difference between the three groups. Pregnancy rates per cycle in the CC and hMG groups were 12.1% and 23.7% respectively with no statistical difference between both groups.Conclusion: Our data indicate that IUI can be performed from 24 hours to40 hours after hCG administration without affecting pregnancy rates and thatboth CC and hMG can be used for induction of ovulation; although the 40 hour insemination and using low dose hMG adds up to a higher chance of pregnancy.