Between 1980 and 1990, 124 patients with Stage Ib endometrioid adenocarcinoma of the endometrium were treated at Massachusetts General Hospital (MGH). Patients were identified from the tumor registry and medical records were retrospectively reviewed. Of the 124 patients, four (3%) developed a recurrence. Eighty-six patients had grade 1 tumors, 32 grade 2 and 6 grade 3. Recurrences developed in two (2%) of the grade 1 tumors, one (3%) of the grade 2, and one (17%) of the grade 3. Of the 86 patients with grade 1 carcinomas, 58 received no adjuvant radiation, 25 received vaginal vault brachytherapy and 3 whole pelvic radiation (WPR). Of the 32 patients with grade 2 tumors, 13 received no adjuvant therapy, 10 vaginal brachytherapy, and 9 WPR. Of the six patients with grade 3 tumors, one received no adjuvant therapy, two vaginal brachytherapy, and three WPR. Of the four women that relapsed, only the patient with grade 3 tumor had been treated with adjuvant radiation (WPR). Three of the four patients recurred at the vaginal vault and all three were salvaged. Stage Ib, grade 1 and 2, endometrioid adenocarcinomas have a good prognosis and adjuvant radiotherapy is not clearly beneficial.