Seventy-two cases of malignant melanoma of the iris treated surgically have been reviewed from Wilmer Institute records with respect to the age, sex, and race of the patients and the clinical and histologic results. Clinical features studied include location and extent of tumor, duration, presence of preexisting lesions, and associated features such as hyphema, glaucoma, cataract, pupillary distortion, and vascularity of the tumor. Surgical therapy included iridectomy, iridocyclectomy and enucleation. Complications of iridectomy included cases of hyphema, cataract, wound dehiscence and episcleral seeding of the tumor. Complications of iridocyclectomy included cases of vitreous loss, cataract, high astigmatism and incomplete excision. Histopathologic features were studied, and the relationship of cell type and tumor cohesiveness to tumor behavior was stressed. Tumor deaths were observed in two of the 72 cases. Clinicopathologic and statistical features in this series of 72 patients were compared with those previously reported series of iris melanomas, and the therapy of these lesions was discussed.