INTRODUCTION: Blood loss and subsequent blood transfusion is a common complication in benign gynecologic surgery that has been understudied. The purpose of this study is to identify risk factors associated with peri-operative blood transfusion and highlight those that are modifiable for abdominal and vaginal hysterectomy. METHODS: Using a retrospective study design between 1/1/2008 and 4/30/2014, 562 of 667 hysterectomies were included. Hysterectomies performed peripartum or for cancer were excluded. Risk factors examined include race, pre-operative hemoglobin, body mass index (BMI), surgical route, and uterine size. Comparisons between subgroups were performed using Chi-square or Wilcoxon test. Blood transfusion rate, odds ratio (OR) of transfusion and its 95% confidence interval (CI) were reported. Multiple logistic regression was used to identify potential risk factors for peri-operative blood transfusion. RESULTS: The overall transfusion rate was 13.3% (75/562) and differed for abdominal versus vaginal hysterectomy (18.0% vs. 6.8% P < .001). Pre-operative hemoglobin less than 10.6 g/dL versus greater than or equal to 13.1 g/dL had five times the odds of transfusion (95% CI 2.4-13.5). Uterus size greater than 470 gm versus less than or equal to 108 gm had fourfold odds of transfusion (95% CI 1.5-14.3). African Americans had twice the odds of transfusion (95% CI 1.2-4.5), despite controlling for increased uterus size and lower hemoglobin. There was no statistically significant association between BMI and transfusion. CONCLUSION: This study identified lower pre-operative hemoglobin, larger uterus size, and African American race as three important risk factors. Prior to hysterectomy, hemoglobin should be optimized above 13.1 g/dL, especially for patients with large uteri and African Americans.