The aim of this study was to compare the efficacy of various dye laser wavelengths in different forms of retinopathies. The study material consisted of 292 eyes of 210 diabetic retinopathy patients treated with dye laser photocoagulation between 1990 and 1992. All the patients were followed for at least 6 months after photocoagulation. Non-proliferative changes (maculopathy and/or preproliferative retinopathy) were present in 135 (46.3%) and proliferative retinopathy in 157 (53.7%) of the eyes undergoing photocoagulation. Of the 157 eyes with proliferative retinopathy, 60 (20.5%) had disc neovascularization, 71 (24.3%) had retinal neovascularization and 26 (8.9%) had retinitis proliferans. Yellow dye laser (580 nm) was applied in 92 (31.5%) eyes, red dye laser (630 nm) in 120 (41.1%) eyes and both yellow and red dye lasers in 80 (27.4%) eyes. There was no significant difference between the different wavelength groups with regard to visual acuity changes before and after treatment (p < 0.01). Overall, the visual acuity was maintained in 56.2% and improved in 25.0% of the eyes. After panretinal photocoagulation, disc neovascularization regressed partially or completely in 47 (78.3%) of the eyes. There was no significant difference among the various laser wavelengths with regard to treatment efficacy judged by the disappearance or regression of disc neovascularization (p < 0.01). All retinal neovascularizations regressed completely with laser treatment, but in 7 eyes (9.9%) new retinal neovascularizations in previously untreated areas developed. Dye laser has not resulted in any complications. It requires lower power settings compared to argon laser and thus facilitates photocoagulation. Another advantage of dye laser is the ability to use yellow and red wavelengths sequentially.