We compared the power required to achieve a retinal burn with the dye yellow laser (wavelength 577 nm) and the argon green laser (wavelength 514 nm) in 49 eyes of 38 patients with proliferative diabetic retinopathy who underwent panretinal photocoagulation. All eyes were treated with both lasers. The dye laser required on average 35.7% less power to achieve a retinal burn than the argon laser (p = 0.0001). With both lasers more power was needed in patients older than 55 years than in those aged 55 years or less and in patients with light skin versus those with dark skin (p less than 0.02). The lower power required with the dye yellow laser allows facilitated photocoagulation in patients in whom treatment with the argon green laser would be problematic.