Nonperfused retinal areas were evaluated in 60 eyes (42 cases) with diabetic retinopathy through repeated fluorescein angiography. Revascularization occurred in the nonperfused area in 40 eyes, due to recanalization in 3 and to intraretinal neovascularization (IRNV) in 39 eyes. Recanalization and IRNV developed in the same fundus in 2 eyes. IRNVs occurred during the nonproliferative state in 11 eyes, concomitant with retinal neovascularization in 14 and after manifestation of proliferative changes in 14. Typically, IRNVs originated from and drained into a retinal venule, showed hairpin-loop at their tips and manifested minimum tendency of dye leakage. No retinal hemorrhage occurred from the IRNVs. Their unexpectedly high incidence and their timely association with retinal neovascularizations point to the importance of IRNVs in the diagnosis of preproliferative diabetic retinopathy.