A review of 306 eyes undergoing pars plana vitrectomy for the complications of proliferative diabetic retinopathy revealed that 26 (8.5%) required a second vitrectomy operation. Among the eyes that required repeat vitrectomy, the eventual visual acuity ranged from 20/20 to 20/400 in 35% and was no light perception in 31%. Reasons for subsequent surgery included recurrent vitreous hemorrhage in 54% of eyes, retinal detachment in 42% and neovascular glaucoma in 4%. Twelve eyes (46%) remained with a permanent retinal detachment despite attempts at surgical repair, and eleven of these twelve eyes subsequently developed rubeosis iridis.