Samples from 17 free-ranging hunter-killed grey brocket deer (Mazama gouazoubira) in the Gran Chaco, Bolivia, were collected during June–August 1999. All 17 deer appeared to be in good condition at the time of death. Gross necropsies were performed, serum was collected for serologic evaluation of selected infectious disease agents, and feces and ectoparasites were collected for evaluation of internal and external parasites. Serologic tests were positive for antibodies against bovine respiratory syncytial virus and four Leptospira interrogans serovars, with questionable results for epizootic hemorrhagic disease virus serotypes 1 and 2. No antibodies were detected to Anaplasma marginale, Babesia bigemina, Babesia bovis, Babesia odocoilei, bluetongue virus (serotypes 2, 10, 11, 13, and 17), bovine viral diarrhea virus, Brucella abortus, foot-and-mouth disease virus, infectious bovine rhinotracheitis virus, Mycobacterium avium subsp. paratuberculosis, and parainfluenza-3 virus. Sixty-four percent (7/11) of the deer had en-doparasites. Amblyomma spp. ticks were found on seven deer, flies of the family Hippoboscidae on six deer, and lice on six deer.