We determined the levels of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in the aqueous and serum in non-insulin dependent diabetic patients with proliferative retinopathy (n = 12) and neovascular glaucoma (n = 11). The aqueous levels of PEGF/VPF were significantly higher in both groups than in 10 diabetics without such complications. The levels were very high in patients with neovascular glaucoma, suggesting that VEGF/VPF is involved in the pathogenesis and progression of diabetic neovascular glaucoma. The serum levels were not significantly related to the presence or the stage of retinopathy. The findings suggest the possibility of treatment of neovascular glaucoma using anti- VRGF/VFP preparations.