To evaluate patterns of failure and overall survival for patients with surgical stage I uterine carcinosarcoma managed conservatively without adjuvant therapy. A computerized database identified 27 patients whose conditions have been diagnosed with surgical stage I uterine carcinosarcoma from 1993 to 2002. Charts were abstracted for patient demographics, tumor characteristics, recurrence, and survival. Of 27 patients, 23(85%) did not receive adjuvant therapy after undergoing total abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic and paraaortic lymphadenectomy. Five patients were stage IA, 14 were stage IB, and 4 were stage IC. Fourteen patients had either poorly differentiated endometrioid carcinoma alone or in combination with papillary serous carcinoma (61%) as their epithelial tumor component. The median nodal count was 9 (range, 3-21). Eleven patients are alive without evidence of disease with a median followup of 63 months (range, 12-164 months). Eleven patients had recurrence with a median time to recurrence of 13 months (range, 6-39 months), and all are dead of disease. Univariate analysis demonstrated that poorly differentiated epithelial or papillary serous histologic diagnosis was the only predictor variable associated with recurrence and, consequently, death (P = 0.04). Approximately 50% of patients with surgical stage I carcinosarcoma who are observed without adjuvant therapy will experience a recurrence. Because most patients will recur distantly, systemic chemotherapy should be considered for patients with early stage uterine carcinosarcoma. ©2009 by IGCS and ESGO.