• A 47-year-old man with a large (20 × 20 × 12-mm) choroidal melanoma in his only eye was treated with helium ion radiation. The patient retained 6/7.5 visual acuity for 2½ years before he was killed in an automobile accident. The eye was ruptured at the time of death; however, histopathologic examination of the eye revealed no residual tumor. The residual ocular mass was composed of eosinophilic amorphous material and macrophages. Necropsy failed to reveal any evidence of metastasis at the time of death. Helium ion charged-particle irradiation in this case was able to completely eradicate the tumor while preserving useful vision.