Fifty eyes of patients with proliferative diabetic retinopathy were followed at frequent intervals to determine the rapidity and stability of retinopathy risk factor regression after argon laser panretinal photocoagulation. Retinopathy risk factors regress rapidly after laser photocoagulation. The incidence of eyes at high risk for severe visual loss (eyes with 3 or more retinopathy risk factors) decreased from 100% prior to treatment to 28% three weeks after treatment. The early response to treatment was a good prognostic indicator of longer term results. Seventy-two percent of eyes which improved from a high- to a low-risk category by three weeks continued to remain at low risk at six months. Sixty-four percent of eyes which failed to improve to a low-risk category by three weeks continued to remain at high risk at six months. The early response to laser panretinal ablation may be used to predict longer-term results.