Lepra bubalorum or leprosy in water buffaloes, is an exotic disease in buffaloes. It is a very interesting phenomenon in Veterinary Medicine because until to date it has been found only in Indonesia. Kok and Rusli (1926) has published their first report in 1926 describing the disease in Java. Since then the diagnosis of leprosy has been established by histological examinations in about 146 water buffaloes (Lobel, 1934). It has also been found in Holstein-Freisen cow (Ressang and Titus, I960), one case in Ongole breed and another in an unidentified cow breed. For leprosy infection in bovine, Kraneveld and Roza (1954) proposed to use the name Lepra bovina Lobel (1934) was the first scientist who brought the attention of this unusual disease to the international scientific world. His extensive works gave vs a clear description of the clinical signs and symptoms, histopathological changes and the microbiological arrangement of the acid fast baccili of the infectious agent in the affected tissues. The changes found in the cutaneous tissue of these animals resembled to those found in the skin of lepromatous lessions in humans. The rod-shape bacteria which is acid fast, are always present in the nodules of the diseases animals. In central Sulawesi (Celebes), leprosy in humans was found as the second most prevalant chronic diseases after pulmonary tuberculosis. It is interesting to know that apparently human leprosy was also found in great numbers in the same area where leprosy in water buffaloes was found frequently. This phenomenon is an interesting subject for investigation to see whether the genus of the bacteria found in humans and that in water buffaloes have the anthropozoonotic properties. * Makalah ini disajikan pada Simposium "Kemajuan Dalam Penyakit Tropis dan Parasit" di Fakultas Kedokteran, Universitas Tarumanagara, Jakarta, 12 Desember 1992 ** Bagian Patologi Anatomi, Fakultas Kedokteran Universitas Tarumanagara, Jakarta, Indonesia. Up to now there are no studies about the microbiological structure of this bacterium in water buffaloes, their biological and immunological characteristics.