Hematochezia from mucosal vascular lesions usually confined to the rectum represents an uncommon but problematic late complication of pelvic radiotherapy. We studied 47 patients with medically refractory hematochezia resulting from radiation-induced rectosigmoid mucosal vascular lesions. All lesions were endoscopically coagulated with Nd:YAG laser. Median duration of hematochezia before laser therapy was 11 months, despite previous medical treatment (98%) or bypass colostomy (6%). Within 3 to 6 months after laser treatment, the number of patients with daily hematochezia fell from 40 (85%) to 5 (11%; p < 0.001), and the median hemoglobin level increased from 9.7 gm/dl to 11.7 gm/dl (p < 0.001). Complications occurred in three patients (6%); no deaths occurred. The condition in six patients (12.8%) was not improved by laser treatment. Two patients (4%) ultimately required surgical treatment for bleeding control. On the basis of symptomatic, hematologic, and endoscopic responses, Nd:YAG laser photocoagulation controlled bleeding from radiation proctopathy in most patients with an acceptably low morbidity. Patients with sigmoid colon involvement responded less favorably. Endoscopic laser photocoagulation should be considered before surgical intervention for treatment of hematochezia from radiation proctopathy.