Mycobacterium avium-intracellulare (MAI) is a non-tuberculous, nonlepromatous or "atypical" mycobacterium now seen frequently in patients with acquired immunodeficiency syndrome (AIDS). In the past decade, the incidence appears to have increased in non-AIDS patients. Although cutaneous involvement is rare, two brothers without detectable immune defects who both presented with cutaneous MAI infection are described; the older brother also has disseminated disease. The cutaneous presentation of MAI, as well as immune and genetic defects that may predispose to mycobacterial infection, are discussed.