Fifty-five collared peccaries (Tayassu tajacu) were collected from October 1988 through April 1991 from five counties within the Trans-Pecos region of Texas (USA) to monitor for diseases and parasites. No endoparasites were recovered on gross examination. Antibody to Borrelia bugdorferi was documented in one (2%) of 55 specimens. Three (6%) of 54 collared peccaries were positive for Yersenia pestis antibodies. All collared peccaries were negative for antibodies against Brucella spp., Francisella tularensis, Rickettsia rickettsii, and Rickettsia typhi. This is the first report of Borrelia sp. and Yersenia sp. pathogens in collared peccaries from this region of Texas.