BACKGROUND Recent studies have demonstrated that a newly described agent of persistent bacteremia, Rochalimaea henselae, and the agent of bacillary angiomatosis are both closely related to Rochalimaea quintana. Bacillary peliosis hepatis seemed likely to have the same etiologic agent as bacillary angiomatosis. We sought these pathologic changes in patients from whom R henselae was cultivated. METHODS For two patients whose histopathologic findings we reviewed, additional light and electron microscopy were performed. Their bacterial isolates were compared by electrophoretic patterns of outer membrane proteins, restriction endonuclease digestion patterns of DNA, and reaction with murine antiserum. RESULTS A previously reported human immunodeficiency virus-infected man with persistent bacteremia due to R henselae was found to have bacillary peliosis hepatis. Rochalimaea henselae was also isolated from the spleen of a woman receiving immunosuppressive therapy after allogeneic renal transplantation. She had developed fever, liver and spleen nodules, and periaortic lymphadenopathy. Bacillary peliosis of her liver and spleen, as well as bacillary angiomatosis of liver, spleen, and a lymph node, were found. The bacterial isolates had comparable electrophoretic patterns of outer membrane proteins and of restriction endonuclease-digested DNA, which differed from the respective patterns of R quintana. Murine antisera raised to the first isolate reacted strongly with the second by means of immunoblot and immunofluorescence techniques, while reacting only weakly with R quintana. CONCLUSIONS Rochalimaea henselae, recently recognized to cause persistent fever and bacteremia in immunocompetent and immunocompromised persons, also causes bacillary angiomatosis and parenchymal bacillary peliosis.