Isolated bone marrow infection by nontuberculous mycobacteria (NTM) is extremely rare. Recently, we encountered a case of bone marrow <i>Mycobacterium avium</i> complex (MAC) infection, which presented as a fever of unknown origin shortly after starting continuous ambulatory peritoneal dialysis (CAPD). The patient was diagnosed with MAC infection on the basis of PCR-restriction fragment length polymorphism analysis and sequencing of DNA obtained from bone marrow specimens. Although this was a case of severe MAC infection, there was no evidence of infection of other organs. End-stage renal disease (ESRD) patients undergoing dialysis can be considered immunodeficient; therefore, when these patients present with fever of unknown origin, opportunistic infections such as NTM infection should be considered in the differential diagnosis.

Keywords: End-stage renal disease, Mycobacterium avium complex, Bone marrow