Bacillary angiomatosis is a newly recognized multisystem bacterial infectious disease seen in the setting of human immunodeficiency virus (HIV) infection. The disease is marked by cutaneous vascular lesions that contain a bacterium similar to the cat scratch disease bacillus. Antibiotic therapy leads to the resolution of both cutaneous and systemic manifestations. Of 17 HIV-infected patients with cutaneous lesions of bacillary angiomatosis, six (35%) had symptomatic osteolytic bone lesions that improved following antibiotic therapy. The authors describe the appearance of the bone lesions on radiographs, computed tomographic (CT) scans, magnetic resonance (MR) images, and radionuclide studies. Osteolytic lesions are a relatively common feature of bacillary angiomatosis in patients with HIV infection. The presence of bone lesions aids in differentiation of bacillary angiomatosis from acquired immunodeficiency syndrome-related Kaposi sarcoma, which has similar cutaneous abnormalities but no associated bone lesions.