An immunocompromised patient with Nocardia brasiliensis pneumonia and empyema acquired disseminated disease due to Nocardia asteroides and died. The treatment of choice for pulmonary or disseminated nocardiosis is 6 to 12 g/day of sulfisoxazole (or adjusted dosage to achieve a serum level of 100 to 150 mg/L) continued for six to 18 months. Combination therapy may be beneficial in selected patients; if trimethoprim therapy is used with sulfonamides, higher than usual doses of trimethoprim may be required to achieve optimal antinocardial activity. When the condition of a patient with nocardiosis fails to improve on sulfonamide therapy, patient compliance should be questioned, serum sulfonamide levels should be measured, cultures and susceptibility studies should be repeated, and a search for sequestered pus should be made. © 1983, American Medical Association. All rights reserved.