The aim was to determine outcome and toxicity in grade 1-2, FIGO stage IC endometrial cancer patients treated with external beam radiotherapy plus vaginal cuff brachytherapy or vaginal cuff brachytherapy alone. Between 1986 and 1999, a total of 132 patients were diagnosed with FIGO stage IC endometrial carcinoma. The median age was 67.5 years (range, 36-88). Median follow-up was 54 months (range, 6-157). Grade 1 disease was present in 64 patients, grade 2 in 45 patients, and grade 3 in 23 patients. Patients with grade 3 disease usually received external radiotherapy and were excluded from this analysis. Of the patients with grade 1-2 disease, 31 received brachytherapy alone and 78 received both external radiotherapy and brachytherapy. Ten (8%) patients experienced failure. Isolated pelvic relapse occurred in five patients. Three patients experienced both distant and local relapse. Two patients had isolated distant relapse. Nine failures occurred in patients treated with both external radiotherapy and brachytherapy. Only one failure occurred in those treated with brachytherapy alone. Overall survival and disease-free survival at 5 years were 85% and 92%, respectively. For those treated with both external radiotherapy and brachytherapy, 5-year locoregional control was 95%. For those treated with brachytherapy alone, 5-year locoregional control was 96.4%. There was no significant survival or local control difference between the two groups. Nine patients (9%) treated with both external radiotherapy and brachytherapy developed Radiation Therapy Oncology Group grade 3-4 toxicity. No patient treated with vaginal cuff brachytherapy alone developed grade 3-4 toxicity (P < 0.001). In patients with well-differentiated (grade 1-2) stage IC endometrial cancer, external beam radiotherapy plus brachytherapy versus vaginal cuff brachytherapy alone achieved equivalent local control and survival. However, vaginal cuff brachytherapy alone produced significantly less toxicity.