The traditional clinical and histopathological prognostic variables and DNA ploidy were analyzed in 46 patients with histologically verified uterine carcinosarcoma. Twenty-three tumors were of the homologous and 23 of the heterologous type. Evaluable flow cytometric DNA histograms from paraffin-embedded tumor tissue were obtained in 39 patients. The overall 5-year cancer related survival was 31%. All tumors were of high malignancy grade. In univariate analysis of survival, extrauterine spread of tumor (P = 0.007), age (P = 0.008), and tumor diameter (P = 0.04) obtained statistical significance. Tumors with components of serous or clear cell carcinomas had a less favorable prognosis (P = 0.017). There was no difference in survival between patients with homologous and heterologous tumors (P = 0.39). Mitotic count, vessel invasion, and DNA ploidy did not obtain prognostic significance. In Cox multivariate analysis, extrauterine spread of tumor (P = 0.004) and age (P = 0.004) were found to be the most important prognostic factors followed by content of serous or clear cell carcinoma components (P = 0.027).