Embryological and clinical efficacy of gonadotropin-releasing hormone (GnRH) antagonist and agonist stimulation protocols in non-obese women with polycystic ovarian syndrome (PCOS) were compared. A prospective randomized study. Medical University Hospital. 70 infertile PCOS patients; 33 in GnRH antagonist and 37 in GnRH agonist group. Similar mature metaphase II oocyte rate (76% vs. 76%) was observed in both protocols. Optimal pronuclear morphology zygotes dominated in both groups (64% vs. 66%). Transferred embryo quality did not differ in both protocols. No significant differences between both protocols were found in delivery rate (p = 0.481), pregnancy rate (p = 0.810), multiple pregnancy rate (p = 0.501), miscarriage rate (p = 0.154), fertilization rate (p = 0.388) and implantation rate (p = 1.000). Duration of stimulation and total follicle-stimulating hormone (FSH) dose were significantly lower in GnRH antagonist protocol (p = 0.0005). GnRH antagonist and agonist protocols in non-obese PCOS patients yield similar embryological and clinical outcomes. Shorter duration of treatment and lower FSH requirement in GnRH antagonist group may be financially beneficial and therefore attractive for patients.