The nonvenereal treponematoses--yaws, endemic syphilis, and pinta--constitute a major health concern for many third world countries. These diseases are caused by an organism that is morphologically and antigenically identical to the causative agent of venereal syphilis, Treponema pallidum. Nonvenereal treponematoses differ significantly in their modes of transmission, epidemiology, and clinical presentation from venereal syphilis. Like venereal syphilis, they have a chronic relapsing course and have prominent cutaneous manifestations. Recently, several cases of imported yaws and endemic syphilis have been described in Europe. With the escalating U.S. military presence in many remote areas of the world and ever-increasing world-wide travel, the diagnosis of the nonvenereal treponematoses must be considered in appropriate clinical and historical situations.