Intravitreal injection of L-ornithine hydrochloride in physiologic saline solution caused marked edema specifically in the pigment epithelium of Sprague-Dawley strain albino and Evans black hooded rats and rhesus and cynomologus monkeys. Swelling of the pigment epithelial cells, which was most prominent four hours after the injection, disappeared by 24 hours. However, many pigment epithelial cells gradually degenerated resulting in patches of denuded areas. The photoreceptor cells overlying the damaged pigment epithelium degenerated secondarily.