The fdariaMonanema martiniwith skin-dwelling microfilariae induces in its natural murid hosts lesions similar to those in human onchocerciasis. This was demonstrated by histo-pathological studies but it appeared useful to evaluate the model by a clinical investigation. An ophthalmological analysis was performed on the two species of hosts, inoculated by one, two, or multiple doses of larvae, and with infections of at least one year duration. A total of 140 eyes was examined (anterior and posterior segments). We established a system for enumerating the different types and severities of lesions. We prepared a file for each eye and attempted to quantify our observations. The significant lesions were different in the two host species. InArvicanthis niloticus, in which motile microfilariae were seen in the anterior segment, punctate keratitis was predominant. InLemniscomys striatus, the posterior segment showed complete chorioretinal atrophy, similar to the final stage of onchocercal chorioretinitis in humans.M. maltinirepresents in its natural hosts two complementary models for the study of the pathogenesis and treatment of human onchocerciasis. Curr. Eye Res. 12: 885-891, 1993.