Note from Dr. Merle A. Sande The number of reported cases of disseminated histoplasmosis in individuals infected with human immunodeficiency virus is increasing, and disseminated histoplasmosis now constitutes one of the critera for establishing a diagnosis of AIDS. Initial infection (inhalation of infected spores) usually takes place in areas along river valleys in the eastern United States. However, because the infection may have occurred during a brief visit to an endemic area in the distant past and is often asymptomatic, historical epidemiological data are often vague or inaccurate. Thus, the physician must consider a diagnosis of histoplasmosis in a member of a group at high risk for AIDS, even though the patient resides in a nonendemic area. Dr. John R. Graybill has a long and distinguished career studying human mycoses. We have asked Dr. Graybill to share with us his thoughts on current approaches to the diagnosis of and therapy for this often rapidly fatal disease.