Of 408 patients with chronic pulmonary histoplasmosis alone, 238 were treated initially with amphotericin B only, 43 with pulmonary surgery combined with amphotericin B, and 27 with pulmonary surgery alone, and 100 were not treated. Among those who received amphotericin B alone and those who were not treated, death was directly related to the age of the patient at the time of diagnosis and, in the treated group, to the stage of disease before therapy. In the treated group death was inversely related to the total initial dose of amphotericin B. There were significantly fewer deaths among patients who received a total dose of over 35 mg of drug per kilogram of body weight than among those who received less. In comparison with the untreated group, there were significantly fewer deaths in the group treated with amphotericin B alone.