Objective Carcinosarcomas are rare and aggressive ovarian malignancies. Treatment recommendations, which include surgical cytoreduction followed by platinum based chemotherapy, have been based on small amounts of retrospective data or extrapolated from experience with high-grade epithelial ovarian adenocarcinoma. Our objective was to determine the effects of radical primary cytoreduction on progression-free survival (PFS) and overall survival (OS). Methods Following IRB approval, records of women with ovarian carcinosarcomas diagnosed between 2000 and 2012 at our institution were reviewed. Demographics, tumor characteristics, treatments, PFS, and OS were collected. Patients were divided into three groups based on the amount of residual disease: > 1 cm of disease, 1 cm of disease, or no visible disease. Chi-square and student's t-test were used to compare variables among groups. Kaplan-Meier survival curves were generated and compared with the log-rank test. Results 51 patients with ovarian carcinosarcoma were identified and all underwent primary cytoreductive surgery. Following surgical cytoreduction, 18 patients (35%) had no visible disease, 20 (39%) had 1 cm of disease, and 13 (25%) had 1 cm of residual disease. Median PFS varied significantly among groups: 29 vs. 21 vs. 2 months (p = 0.036) as did median OS: 57 vs. 32 vs. 11 months (p = 0.015). When patients with stage 3 disease were analyzed separately, median OS still varied significantly among groups: 57 versus 31 versus 3 months (p = 0.009). Conclusion Degree of surgical cytoreduction appears to correlate with PFS and OS. Radical surgery resulting in no visible disease is recommended for the upfront surgical treatment of ovarian carcinosarcoma. © 2014 Elsevier Inc.