<h3>Objectives:</h3> Mutations in <i>BRCA1</i> and <i>BRCA2</i> increase the risk of epithelial ovarian cancer (EOC). Emerging evidence suggests obesity may influence <i>BRCA</i> tumor biology; body mass index (BMI) appears to correlate with DNA damage in breast epithelium in <i>BRCA</i> women. We hypothesized that obesity negatively influences tumor biology in <i>BRCA</i> women with EOC, and sought to identify correlations with BMI and clinical outcomes in this population. <h3>Methods:</h3> We performed an IRB approved retrospective study. We identified patients with <i>BRCA</i>-associated EOC diagnosed between 1990-2015. All women underwent surgical resection with platinum-based chemotherapy. We abstracted clinical and pathologic data, and calculated BMI at the time of diagnosis. Obesity was examined per WHO criteria of normal weight, overweight, class I obesity, and class II obesity. We performed descriptive statistics with Kaplan-Meier, Cox Proportional Hazards Regression, and univariate analyses. <h3>Results:</h3> We identified 179 women meeting criteria. Most were <i>BRCA1</i> (125, or 70%); 53 (30%) were <i>BRCA2</i>; and 1 had both a <i>BRCA1</i> and <i>BRCA2</i> mutation. The majority had stage III/IV disease (137, 77%) and grade 3 serous histology (168, 94%); 150 patients underwent optimal cytoreduction (87%). BMI was distributed throughout the WHO strata: 101 women had normal weight; 46 were overweight; 20 had class I obesity; 12 had class II obesity. Age, medical comorbidities, and rates of optimal surgical cytoreduction were similar among these groups. In a subcohort of patients with stage III/IV disease, we identified a significant trend between increased BMI strata and poor disease-free survival (35, 32, 25, and 13.5 months, <i>p</i>=0.003). This was also observed for overall disease-specific survival (132, 144, 112, and 72.5 months, <i>p</i>=0.0306). Multivariable analyses of the entire cohort confirmed that age (<i>p</i>=0.035), stage (<i>p</i><0.001), and BMI (<i>p</i>=0.017) remained significant independent prognosticators after controlling for grade and optimal cytoreduction. <h3>Conclusions:</h3> We identified a significant and independent association between BMI and clinical outcome in <i>BRCA</i> positive women with EOC. Factors associated with obesity may negatively influence <i>BRCA</i> associated ovarian cancer biology, and suggest this may be a modifiable risk factor to target for therapy.