The authors evaluate the results of treatment of proliferative diabetic retinopathy by panretinal photocoagulation with an argon laser in a group of 122 eyes, 89 patients, with a mean follow-up period of 4.7 years. They achieved complete regression of revascularization of 69% eyes, partial regression in 21% eyes. In 10% eyes they treatment failed. The resulting visual acuity was 6/12 and better in 41% eyes, a visual acuity worse than 6/60 was recorded in 11% eyes. It remained unaltered in 70% eyes, deteriorated in 19%. The authors evaluated the success rate of laser photocoagulation in relation to the stage and site of neovascularizations. They found that the poorest reaction to panretinal photocoagulation is obtained in advanced neovascularization of the disc and they remain of the known view that advanced neovascularizations display a certain grade of autonomy which is the cause of a poorer response to panretinal photcogaulation. They confirm former observations that if signs of regression of neovascularization develop early, within 3-6 weeks after the onset of laser photocoagulation this may be considered a prognostically favourable sign.