Eight patients with proliferative diabetic retinopathy developed extensive retinal arteriolar and capillary obstruction. Ophthalmoscopy showed many white, thread-like retinal arterioles associated with capillary and venous dilatation. Widespread retinal arteriolar and capillary nonperfusion was demonstrated by fluorescein angiography. Ischemic maculopathy resulted in severe loss of visual acuity in some eyes. The severe degree of retinal ischemia was accompanied by optic disc pallor and neovascularization and a high incidence of rubeosis iridis with neovascular glaucoma. Patients with this variety of diabetic retinopathy have a poor prognosis of retaining useful vision.