OBJECTIVE To assess the usefulness of a short regimen in ovulation induction in an in vitro fertilization (IVF) program. DESIGN A prospective randomized trial was set up to compare long and short regimens of gonadotropin-releasing hormone agonist administration for ovulation induction in IVF. SETTING Aberdeen Assisted Reproduction Unit. PATIENTS Eighty-seven patients undergoing IVF were randomized between the two protocols. Stimulation regimen was the only variable being tested. MAIN OUTCOME MEASURES Stimulation response and occurrence of luteinizing hormone (LH) surges. RESULTS There was no difference in the stimulation requirements, response to stimulation, number of follicles aspirated, or the number of oocytes obtained. The fertilization rates, number of embryos transferred, and pregnancy rates were also similar in both groups. Like the long regimen, it prevents the occurrence of a premature LH surge. CONCLUSION The short regimen is a useful and cheaper alternative in ovarian stimulation of patients undergoing IVF.