PURPOSE: We investigated the therapeutic possibilities of gamma brachytherapy to improve the final functional results of eyes with choroidal hemangiomas, which are benign vascular tumors that can induce progressive impairment of visual acuity. METHODS: We treated 41 patients with choroidal hemangioma with cobalt-60 applicators. The lesions consisted of 39 circumscribed hemangiomas and two diffuse hemangiomas in patients with Sturge-Weber syndrome. Before treatment, visual acuity in the affected eye was 20/200 in ten patients, 20/200 to 20/50 in 17 patients, 20/40 to 20/25 in 11 patients, and 20/20 in three patients. All patients were symptomatic. The macula was infiltrated by the tumor in 12 eyes (29.3%). There was retinal detachment in 40 eyes (97.6%), cystoid edema in ten eyes (24.4%), subretinal fibrosis in eight eyes (19.5%), and areolar atrophy in two eyes (4.9%). RESULTS: After treatment, the retina was reattached in all eyes, and the tumor progressively transformed into a flat scar. The postirradiation macular lesions that we identified were pigment migrations in the macular region, subretinal fibrosis, and an areolar atrophic scar. We correlated the functional results at two, five, and ten years after treatment with the initial visual acuity, and with pre-existing and posttreatment macular lesions. CONCLUSIONS: Our results suggest that radiotherapy is a valuable therapeutic modality for choroidal hemangiomas, particularly in hemangiomas that involve the macula, and for tumors associated with bullous retinal detachment.