Forty-four uveal melanomas were evaluated for patterns of tumor regression after proton beam irradiation. All tumors were followed for a minimum of ten months after treatment. Seven lesions completely disappeared, 33 have decreased in size, and 4 remained unchanged. Associated signs of tumor regression were: resolution of the secondary serous retinal detachments, central apical yellow discoloration of the tumor, destruction of the tumor's vasculature, and elimination of fluorescein leakage. This study demonstrated that regression after proton beam irradiation is a relatively slow process, and the effects of radiation could be observed in some cases more than a year after treatment.