Objective: To analyze the prognostic factors in endometrial stromal sarcoma (ESS). Methods: Prognostic factors and adjuvant treatment of endometrial stromal sarcoma in 25 patients were evaluated retrospectively. Results: The mean age of the group was 43. In 58% of the patients, the presenting sign was vaginal bleeding. The median total survival was 55 months while the disease free survival (DFS) was 49 months. Disease recurred in eight patients, in three of whom tumors were confined to the pelvis. Seventeen patients were alive without disease. Four patients died because of the disease. The 5-year survival rate for patients with low-grade (LGESS) disease was 92%, and 85% in high-grade (HGESS) disease. Conclusion: In multivariate analyzes, tumor grading was the only prognostic factor in endometrial stromal sarcoma (P = 0.0026). (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.