Five patients having the "eruptive form" of Carrion's disease were found to have bacteria in the fine fibrillar interstitium of the verrugas. Features suggesting phagocytosis of the organisms by the verruga cells were observed. The bacteria are probably Bartonella because they are similar to Bartonella that parasitize red blood cells in the hematic phase of the disease. It is likely that after the hematic phase, unknown mechanisms, probably related to immunity, drive Bartonella organisms to the skin where they are destroyed and eliminated in the verrucous tissue. This suggests that verrucous tissue develops in order to eliminate Bartonella during the tissue phase of the disease.