Pinta is a dermatrophic treponemal disease with immunologic similarities to syphilis but without its generalized and serious consequences. Workers in treponemal immunology have long been intrigued with the possible use of Treponema carateum, the causative agent of pinta, to confer immunity to syphilis.1 Failure in attempts to establish the disease in experimental animals has impeded the laboratory study of the organism. However, chimpanzees have not heretofore been studied under controlled conditions for their susceptibility to inoculation with T carateum from humans with pinta. The susceptibility of chimpanzees to human syphilis, as reflected in current studies at the Venereal Disease Research Laboratory, and the close immunologic relationship of chimpanzees to man, prompted exploration of the premise that T carateum might also be transferable to these animals. Because pinta does not occur in the United States but can be found to occur to a limited extent in Mexico, a collaborative effort