Objective: To evaluated the association between obesity and the outcome of superovulation and intrauterine insemination (IUI) in infertile ovulatory women. Design: Retrospective chart review. Setting: University-based infertility clinic. Patient(s): Three hundred thirty-three ovulatory women, grouped by body mass index (BMI) categories, who received superovulation and IUI for treatment of infertility. Intervention(s): None. Main Outcome Measure(s): Primary outcome: cycle fecundity. Secondary outcomes: total dose of gonadotropins serum level of E-2, and number of follicles >= 17 mm on the day of hCG injection. Results(s): Adjusted cycle fecundity was not different among BMI groups (underweight: 0.14 [95% CI: {0.07, 0.29}], normal weight: 0.12 [95% CI: {0.09, 0.16}], overweight: 0.17 [95% CI:{0.12,0.24}], and obese: 0.14 [95% CI: {0.08, 0.23}]). Adjusted total gonadotropin dose (IU/cycle) was greater in obese women than in underweight or normal weight women. Although the numbers of large follicles were not different, E-2 levels (pg/mL) were lower in obese women than in normal-weight and over-weight women. Conclusion(s): Our sample of ovulatory infertile women demonstrated that treatment-related cycle fecundity is unaffected by obesity, We conclude that obese, infertile ovulatory women require a greater dose of gonadotropins to achieve similar levels of superovulation than normal, underweight or overweight women.