Botryomycosis in an uncommon chronic bacterial infection that mimics fungal disease clinically and histologically. Microscopically the hallmark of the disease is the presence of fungus-like granules in which the causative organism is embedded. A patient with typical cutaneous botryomycosis is presented, along with the immunologic abnormalities discovered on laboratory examination. The botryomycosis literature is reviewed, with special emphasis on the immunologic status of the host. Additional studies of the causative organism and cell-mediated immunity in the host in future patients with botryomycosis may help to further elucidate the pathogenesis of this most interesting disease.