Bacillary angiomatosis is an opportunistic infection with systemic manifestations. Although most cases have occurred in human immunodeficiency virus-positive patients, other immunosuppressed patients, and even seemingly immunocompetent individuals, can become infected. In addition to the well-characterized cutaneous manifestations, visceral involvement can occur and may be the only locus of infection. Lymphadenopathy, bone or soft-tissue masses, fever, and hepatosplenomegaly can be presenting signs. The causative bacterium is still unidentified, but resemblances to the rickettsiae, Rochilamea quintana, the recently identified cat-scratch disease bacillus, and Bartonella bacilliformis have been noted by various investigators. Systemic disease is treatable and can be cured with antibiotic therapy.