Vitrectomy was performed to treat 74 consecutive eyes for complications of diabetic retinopathy. Eight (13%) of 61 eyes followed up for an average of 12 months developed anterior hyaloidal fibrovascular proliferation. This was the most common postoperative complication, whose features included recurrent hemorrhages into the vitreous cavity or anterior vitreous, or both; vessels or fibrovascular tissue on the posterior lens capsule; anterior extraretinal vascularization extending toward the lens on the anterior hyaloid; traction detachment of the peripheral retina or ciliary body; and hypotony. Patients who developed this complication tended to be young males with severe retinal neovascularization and extensive retinal ischemia; traction retinal detachment as an indication for surgery; placement of a scleral buckle; postoperative rubeosis iridis, recurrent vitreous hemorrhages, and retinal detachment; and multiple surgeries. Four eyes progressed to atrophia bulbi. Early recognition followed by additional surgery in two patients and extensive additional photocoagulation in two other patients was successful in preserving good visual function.