Mycobacterial infections in renal transplant recipients are unusual. But mycobacterial infection is not uncommon in Korea. We retrospectively analyzed the kidney recipients with mycobacterial infection in Severance Hospital from 1979 to 1994. The results of our study were as follows: l) The incidence of mycobacterial infection was 4.5%(57 cases of l256 case.,) which was higher than that of normal Korean population(=1.8%) 2) The extra-pulmonary mycobacterial infections were relatively more common(=21.1%) than normal population. 3) The median onset of mycobacterial infections after kidney transplantation was 40.2 months. Almost all the cases(44/57, 77.2%) of mycobacterial infection were occurred within 5 years after kidney transplantation. 4) The risk factors affecting the incidence of mycobacterial infection were type of immunosuppressive agent and the presence of hepatitis B virus antigenemia. 5) The result of anti-tuberculosis medication for the pulmonary mycohacterial infection was excellent under the careful monitoring of immunosuppression, but that of extra-pulmonary mycobacterial infection wa poor. Most of mortality by mycobacterial infection were occurred among the extra-pulmonary infection cases. 6) There was no statistically significant influence on the patient and graft survival in patient with rnycobacterial infection, but there was a trend of decreasing long term survival in these patients.