PURPOSE: To present a large series of choroidal hemangiomas treated with proton beam irradiation and to describe the treatment outcomes. METHODS: We treated 54 eyes of 53 patients with choroidal hemangioma. The lesions consisted of 48 circumscribed hemangiomas and six diffuse hemangiomas in patients with Sturge-Weber syndrome. The total applied dose was 27.3 Gy in four eyes, 22.7 Gy in three eyes, and 16.4 Gy to 18.2 Gy in 47 eyes. RESULTS: The retina reattached within six months after treatment in all 54 eyes and no recurrence of the secondary retinal detachment occurred within the follow-up period of 6 months to 9 years. Tumors treated with the higher doses regressed faster than tumors treated with the lower doses, but radiation-induced complications of the optic nerve appeared in all four eyes treated with a total dose of 27.3 Gy. Of 31 eyes treated with 16.4 to 18.2 Gy and followed for more than 1 year, 22 had an improvement in their visual acuity, and nine retained the same visual acuity. At the last follow-up examination, the best-corrected visual acuity was 20/20 or better in nine eyes, 20/40 to 20/25 in 13 eyes, 20/100 to 20/50 in six eyes, and 20/200 or less in three eyes. CONCLUSIONS: Proton beam irradiation of choroidal hemangiomas appears to be a valid therapeutic alternative. A total proton dose ranging from 16.4 to 18.2 Gy applied in four daily fractions seems adequate to ensure local control of both tumor and secondary retinal detachment.