A case of disseminated histoplasmosis in an elderly woman is presented to point out some of the features of host-parasite interaction and to bring attention to some unusual manifestations. It is apparent that disseminated, active histoplasmosis may be found in the absence of remarkable constitutional signs and symptoms. The presence or absence of skin and complement fixation-test reactivity depends on many variables including age of the patient, severity of the disease, and drug therapy. The involvement of two unusual sites, the knee joint and vagina, is discussed in relation to the more usual distribution of lesions. The warning that the effects of any therapy must be evaluated in light of the knowledge that even disseminated cases can undergo spontaneous resolution is emphasized.