Abstract.Between September 1979 and December 1985, 124 eyes of 105 patients underwent vitrectomy for diabetic eye disease. Until May 1987 (mean follow‐up of 3.2 ± 0.3 years) neovascular glaucoma (NVG) occurred in 21 eyes (17%); in 18 of them within the first post‐operative year. Post‐operative total retinal detachment (P= 0.0003) and pre‐ and/or per‐operative aphakia (P= 0.0047) proved to be significant independent risk factors for post‐operative NVG (odds ratio 9.9 and 4.6, respectively). The rate of NVG decreased from 22% in the second half of the study period (NS). This decrease may be related to smaller proportion of aphakic vitrectomies in the latter half (50% vs 18%,P<0.0004). Lack of previous panretinal photocoagulation did not increase the risk of NVG significantly. Of the 84 non‐vitrectomized fellow‐eyes NVG occurred in 17. In 4 of the 21 eyes the intraocular prressure (IOP) was satisfactorily controlled by antiglaucomatous medication after retinal panphotocoagulation, direct photo‐coagulation of the iris new vessels and/or cyclocryocoagulation. Four eyes remained hypertonic, but were comfortable with symptomatic medication, 12 eyes became hypotonic. One eye was enucleated. Useful vision was preserved in 3 eyes, light perception (LP) in 2 eyes, the remainding 16 lost LP. In 13 of the 16 eyes vision was lost within the first p