Between 1979 and 1989, I examined 106 patients (16 pedigrees) with signs of familial exudative vitreoretinopathy. Of these patients, 101 had familial exudative vitreoretinopathy, and five had a sporadic manifestation. The complications of familial exudative vitreoretinopathy, deformation of the posterior retina, vitreous hemorrhage, amblyopia, and retinal detachment, caused diminished visual acuity. Of 170 eyes, retinal neovascularization was observed in 18 eyes (11%), and retinal exudates were observed in 16 eyes (9%). Several forms of retinal detachment occurred in 37 of 180 eyes (21%), which often took an unfavorable course. A falciform retinal fold was observed in 14 eyes (8%). Retinal surgery was performed in 14 eyes; reattachment of the retina was successful in only seven eyes. Platelet aggregation studies disclosed no significant differences between seven patients with familial exudative vitreoretinopathy and ten control subjects. The pathogenesis of the disease is based on a premature arrest of the vascular development of the retina.