Tuberculosis (TB), caused by Mycobacterium tuberculosis, has been one of three major infectious diseases in the world inflicting more than 8.7 million new cases and 1.3 million deaths each year. M. tuberculosis was reported to transmit from humans to a variety of animals including dogs, cattle, non-human primates, elephants, and birds, and secondary transmission of M. tuberculosis between animals was also reported resulting in back transmission to humans as a zoonosis. Meanwhile, bovine TB, caused by M. bovis, has been on the top list of zoonoses comprising about 30% of human tuberculosis in Europe before introduction of pasteurization of milk in the early 20th century. Although WHO claims that only 3.1% of all human TB cases are due to M. bovis infection, its rate varies depending of countries from 0.5 ~ 2.0% in the US and European countries to 5% in Nigeria, 7% in Uganda, and 13.8% in Mexico. M. bovis also can infect much wider range of animals, particularly wildlife animals as natural hosts and reservoirs, notably white-tailed deer, African buffalo, brush tail possum, European boar, Eurasian badger. Therefore, these animals can be also a source of human infection of M. bovis. Although there is still a controversy, M. avium subspecies paratuberculosis has been claimed as a cause of a portion of Crohn’s disease in humans. In addition, there are as high as 40 mycobacterial species including M. avium, M. kansasii, which can be found in animal tissues such as lymph nodes of cattle, which are potential source of human infections. Although chances are very rare in Korea, active control programs against mycobacterial infections, particularly M. bovis infection in animals are desirable to prevent further human infection considering that mycobacteria can survive in biofilm, soil, and amoeba in water.