• Proton beam irradiation was used in the treatment of 76 uveal melanomas from July 1975 to December 1980. Five (7%) were small, 32 (42%) were medium, and 39 (51%) were large melanomas. The follow-up period ranged from two months to 5½ years; 19 patients were followed up for more than two years and 39 were observed for more than a year. Tumor regression has been achieved in all eyes with more than 12 months of follow-up except one, which was enucleated because of secondary complications. Three patients in whom metastatic disease developed died. Our data indicate that proton irradiation can be used for the treatment of relatively large lesions that previously were considered untreatable and reduces the high ocular morbidity experienced with other methods in the treatment of medium and small melanomas.