Clear-cell carcinoma (CCC) of the endometrium is a relatively rare malignancy that is considered to be one of the most aggressive types of endometrial carcinoma. To evaluate the behavior of low-stage (stages I and II) CCC of the endometrium, we retrospectively reviewed 17 such cases seen at The University of Texas M.D. Anderson Cancer Center from 1963 to 1990. Patients' ages ranged from 52 to 81 years. Fifteen cases were pure CCC, and two cases were predominantly CCC with a focus of endometrioid adenocarcinoma FIGO grade I. All patients have been followed-up for at least 3 years. At the time of the study, six patients were alive without disease, one patient was alive with disease, five had died of other causes, and five had died of disease. The estimated survival rate was 71%. Estimated 5-year survival rates for endometrioid adenocarcinoma FIGO grade III and uterine papillary serous carcinoma are 73 and 39%, respectively. We conclude that patients with low-stage CCC of the endometrium have a survival rate similar to that of patients with endometrioid adenocarcinoma FIGO grade III and better than that of patients with uterine papillary serous carcinoma of similar stages.