Disease caused by Brucella ovis has not been previously reported in bighorn sheep (BHS; Ovis canadensis canadensis). Antibodies to B. ovis, however, are occasionally detected in free-ranging BHS, and this has been a concern for managers involved in translocation programs. To investigate the pathogenesis of B. ovis infection in this species, 20 BHS (10 male, 10 female) were inoculated intraconjunctivally (IC) with 5.4 × 10(8) colony forming units (cfu) B. ovis. Six BHS (three male, three female) received 1 mL phosphate-buffered saline IC and served as in-contact control animals, and eight BHS (one male, seven female) received 1 mL phosphate-buffered saline (PBS) IC and served as noncontact controls. In addition, 14 domestic sheep (Ovis aries, nine male, five female) were inoculated IC with 5.4 × 10(8) cfu B. ovis (positive controls), and five domestic sheep (three male, two female) received 1 mL PBS IC (contact controls). All domestic sheep were housed separately from BHS. Bighorn sheep experimentally infected with B. ovis became antibody and culture positive and developed clinical signs of B. ovis infection including abortion and epididymal and testicular swelling. Lesions in BHS were consistent with, and in some cases more severe, than those observed in domestic sheep. Antibodies against B. ovis were detected within 4 wk postinoculation and remained positive until the end of the study. These findings have important implications for BHS management.