One hundred twenty-five retinochoroidal photocoagulation burns, produced by a transpupillary diode laser (810 nm) in six eyes of three cynomolgus monkeys, were evaluated by clinicopathologic correlation for up to 9 weeks after laser treatment. Diode burns of clinical grade 2 strength were comparable to those described for argon laser. However, diode burns of clinical grade 3 strength produced choroidal changes more intense than those described for argon laser. Where present underneath photocoagulation sites, ciliary nerves in choroid or sclera consistently showed scarring. Prospective randomized controlled clinical trials to document possible clinical equivalence or superiority of diode treatment have not yet been performed. Potential clinical advantages of the diode laser include its weight, size, durability, price, absence of visible flash, and its ability to produce burns that profoundly affect the choroid.