The authors report two cases of peliosis hepatis, occurring in patients with AIDS, who presented a persistent fever and an hepatomegaly. The liver biopsies showed areas of peliosis, where bacilli were observed by Warthin-Starry stain. In one case, techniques of molecular biology allowed the identification of Rochalimaea henselae, pathogen involved in bacillary angiomatosis. This rickettsia has been newly recognized in the United-States, where 17 cases of bacillary peliosis have been published in immunocompromised hosts and mainly in patients with AIDS. These observations illustrate the clinical and histological features of this new opportunistic infection, as it is described in the literature. The clinical signs include an unexplained fever, an hepatomegaly, and in 75% of the cases, a splenomegaly. The cutaneous lesions of bacillary angiomatosis are associated in 40% of the cases. An antibiotic treatment by erythromycin ensures a complete recovery.