Most patients with pulmonary histoplasmosis experience a self-limited illness that rarely requires treatment. However, patients who inhale a large burden of organisms from the environment and those who are immunosuppressed may develop severe, life-threatening pneumonia. Chronic histoplasmosis occurs almost exclusively in patients with severe chronic obstructive pulmonary disease. Complications of pulmonary histoplasmosis are mostly related to persistent mediastinal lymphadenopathy. Mild to moderate forms of pulmonary histoplasmosis should be treated with itraconazole. Patients with severe pulmonary involvement should initially receive amphotericin B; after the patient's condition has improved, therapy can be changed to itraconazole. Preventive measures should be used to protect workers from exposure to large numbers of Histoplasma capsulatum organisms.