The cases of seven patients with diabetes mellitus and peripheral proliferative retinopathy (retinal neovascularization at or anterior to the equator) were studied. Associated abnormalities found included systemic arterial hypertension in five, a positive fluorescent treponemal antibody titer in four, and benign monoclonal gammopathy, intravenous drug abuse and hemoglobin AS each in one patient. The presence of additional systemic diseases should be suspected in diabetic patients with predominantly peripheral proliferative retinopathy.