OBJECTIVE: The aim of this study was to determine the possible predictors of total gonadotropin dose (TGD) required to achieve ovulation in patients with unexplained infertility or male subfertility. STUDY DESIGN: A prospective study on 230 patients (n:178 unexplained infertility, n:52 male subfertility) scheduled for controlled ovarian stimulation (COH) and intrauterine insemination (IUI) was designed to determine the association between basal follicle stimulating hormone (FSH), luteinizing hormone (LH), estrodiol (E2) levels, antral follicle count (AFC), age and body mass index (BMI) and total gonadotropin doses needed to achieve follicular growth. RESULT: Regression analysis revealed an association between basal FSH level, BMI and AFC with total gonadotropin dose (P=0.001, P=0.002, P=0.045). BMI was positively correlated with TGD (r:0.400, P=0.001). Mean BMI of patients who required a total dosage of >1500 IUs of gonadotropin was 29.7±4.8kg/ m2 where as it was 24.9±3.2kg/ m2 for patients who received <1500 IU to achieve follicle growth (P=0.001). CONCLUSION: Our study results imply that basal BMI is the essential parameter in determining the total dose of gonadotropin used to achieve follicular growth.