The clinical and histologic findings in five cases of endometrial cancer, which developed following radiation therapy for squamous cell carcinoma of the cervix, are described. The mean age at endometrial cancer diagnosis was 69 years and average latency period from initial therapy to development of endometrial carcinoma was 13.4 years. For endometrial cancer, one patient had Stage Ib, one patient had Stage IIIa, two patients had Stage IIIc, and one patient did not undergo laparotomy. The histological types were carcinosarcoma in two patients, endometrioid adenocarcinoma, grade 3 in one patient, and clear cell carcinoma in one patient. All patients died of disease within 33 months of diagnosis. Endometrial cancers that develop after radiation treatment have a preponderance of high-risk histological subtypes, and consequently have a poor prognosis. Long-term follow-up should be mandatory for patients surviving radiation therapy for cervical cancer in order to detect and effectively treat second malignancies.