OBJECTIVE To measure erythropoietin (Epo) levels in the vitreous body from patients with proliferative diabetic retinopathy (PDR). METHODS Undiluted vitreous samples were obtained from 44 patients who had not undergone prior vitreous or intraocular surgery. Patients were divided into two groups: A (n= 24) patients with PDR and B (n= 20) patients with retinal detachment, preretinal macular membranes and macular holes. Epo was determined using radioimmunoassay. RESULTS Epo vitreous concentration in group A was 512 mU/mL (range 120-880) and in group B was 25.1 mU/mL (range 5.2-201) (p< 0.001). CONCLUSIONS These results show that the concentration of Epo in the vitreous body was significantly higher in patients with PDR than in the control group.