We performed laser iridotomy and trabeculotomy on Rhesus and Cynomologous monkeys with a Britt Model 152 repetitively pulsed argon laser. The total energy delivered varied from 2 to 6 joules. The easiest sites for laser iridotomy were at 3 and 9 o'clock. The iridotomy remained open for at least 2 months. Scanning electron microscopy confirmed that no damage occurred to the lens. After laser burns to the trabecular meshwork light microscopy showed anterior synechiae, corneal endothelial swelling and trabecular coagulation. Scanning electron microscopy showed that only a few holes were made in the trabecular tissue, even after a massive dose; some of them appeared to lead directly to the canal of Schlemm. We feel that although this machine can be used successfully to perform iridotomy in humans, it cannot replace the current surgical procedures in glaucoma.