Since the beginning of the AIDS epidemic, nontuberculous mycobacterial infections have been reported with increasing frequency in HIV-infected patients. Although Mycobacterium avium complex has been responsible for the majority of these infections, an increasing number of other nontuberculous mycobacteria have been reported to cause clinical disease. In spite of initial questions about the clinical significance of disseminated M avium complex infection, it now appears that this infection contributes to the morbidity and mortality of HIV-infected patients. Therefore, recent studies have focused on the use of antimycobacterial drugs to treat or prevent M avium complex bacteremia. These studies have found that drug treatment, especially with the newer macrolides, can decrease bacteremic load and improve debilitating symptoms. Furthermore, rifabutin have been found to decrease or delay the development of M avium complex bacteremia. As HIV-infected patients live longer because of antiviral drugs or prophylaxis against opportunistic infections, nontuberculous mycobacterial infections will likely become increasingly frequent and contribute to substantial morbidity or mortality.