e16528 Background: Obesity is an epidemic public health problem in the United States. In gynecologic oncology, obesity is an established risk factor for endometrial cancer. However, its role in the pathogenesis and survival in ovarian cancer is debated. Recent studies have attempted to elucidate a possible relationship, but variations in design and heterogeneity in patient characteristics make it difficult to draw definitive conclusions. The purpose of our study was to determine if body mass index at the time of treatment initiation for high grade serous ovarian carcinoma has an effect on patient outcome. Methods: Nine-hundred four patients treated for ovarian cancer at M.D. Anderson Cancer Center were identified between 2002 and 2007. Patients were excluded for low grade or non-serous histology, neoadjuvant treatment, or if presenting with recurrent disease. Clinicopathologic data were extracted by retrospective chart review. Patients were stratified by body mass index (BMI) as normal (BMI<25), overweight (BMI 25-<30), or obese (BMI>30). All were treated with primary cytoreduction and standard platinum/taxane chemotherapy. Chemotherapy was dosed using adjusted body weights. Outcomes included time to recurrence, overall survival, success of surgical debulking, and chemotherapeutic toxicities. Statistical analysis was performed using Fisher's exact test, Wilcoxon test, and Kaplan-Meier estimates. Results: A total of 127 patients were included for analysis. Patients were followed for a mean of 37 months (range 3–86 months). Twenty-one patients were obese (16.5%), and 35 were overweight (27.5%). Diabetes was more prevalent in the obese cohort (p = 0.0038). There was a trend towards greater likelihood of suboptimal debulking in obese patients, but this did not reach statistical significance (p = 0.06). BMI had no effect on recurrence-free survival (HR 0.69 [CI 0.39–1.23], p = 0.21) or overall survival (HR 0.95 [CI 0.68–2.43], p = 0.91). There was no difference in chemotherapy side effects or chemoresistance across BMI strata. Conclusions: Body mass index has no effect on survival in women with high grade serous ovarian cancer. Effectively managing comorbidities and ensuring adequate chemotherapy dosing in the obese patient is crucial for optimizing outcome. No significant financial relationships to disclose.