PURPOSE: To describe the clinical features of patients with advanced proliferative diabetic retinopathy who underwent vitrectomy and were found to have subretinal hemorrhages. METHODS: The authors conducted a retrospective study of 49 patients with complications of proliferative diabetic retinopathy requiring pars plana vitrectomy and demonstrating the presence of subretinal hemorrhage. Preoperative, intraoperative, and postoperative clinical characteristics were evaluated. Patients were observed for a minimum of 6 months. RESULTS: The location, size, and clearance of subretinal hemorrhages revealed wide variation. Forty-two patients had focal subretinal hemorrhages, and 14 patients within this group had submacular hemorrhages. A retinal break was observed in 15 patients (31%). Only one patient required drainage of the subretinal hemorrhage to achieve retinal reattachment. Vitreous surgery resulted in 59% of patients achieving a visual acuity > or = 5/200. Seventy-nine percent had stable or improved vision, whereas 20% had worse vision after surgery. CONCLUSION: Subretinal hemorrhages appear to be an uncommon feature associated with long-term, advanced proliferative diabetic retinopathy and portend a guarded visual prognosis. These hemorrhages may occur spontaneously in previously untreated eyes and are often unsuspected until observed at the time of vitreous surgery. In general, removal of subretinal hemorrhages was not necessary to achieve macular anatomic attachment, and most patients experienced improved visual function after surgery. Diabetic subretinal hemorrhages may indicate a retinal break, and, therefore, careful ophthalmic inspection should be performed in these patients.