Rhesus specimens were infected with recently isolated cultures of L. brasiliensis. The inoculations were made intradermically into the superciliary arches and, exceptionally, into the skin of the nose. The incubation period from 1 to 2 months. The course of the infection varies according to the extention of the lesios if limited to the skin of invading the mucous membranes. In the first case, the infection lasted form 3 to 8 months and always termninated in spontaneous cure. When the changes extend to the mucous membranes, they persist and evolute, whilst the skin changes observed on the same animal become regressive and tending towards cicatrization and cure. Also dogs were inoculated with positive results. The inoculation were carried out by intradermic way into the skin of the nose. The incubation period was of about 2 months and the changes observed were confined to the skin and terminated in cure. One agouti (Dayprocta agouti) was inoculated but was not infectes. One Rhesus which recovered from an infection by L. brasiliensis, reinoculated with another strain of the same parasite, was also not infected. The extent of the changes to the mucous membranes, in experimental infections of Rhesus by L. brasiliensis, a fact not yet observed in L. tropica, consitutes one more argument in favour of the independence of the species.