We report a case of tuberculosis due to infection with Mycobacterium bovis in an elderly male black rhinoceros (Diceros bicornis minor) from the Limpopo Province in South Africa. The animal was euthanized due to very poor condition, old age, and dental attrition. Necropsy examination revealed two small nonencapsulated granulomas (approximately 40-mm diameter) in the dorsocaudal lobe of the left lung. Sequencing of isolated crude lung tissue PCR product and boiled lung culture samples confirmed that the causative organism was M. bovis. Genotyping revealed limited similarities with M. bovis strains isolated thus far from South African cattle or wildlife. The source of the infection could not be determined. This case illustrates that M. bovis could impact conservation of free-ranging rare and endangered species. Effective diagnostics are urgently needed for different animal species, such as white or black rhinoceroses, to certify with a reasonable degree of certainty that these animals are free of tuberculosis in natural habitats.