Case histories of 25 consecutive patients with acquired immunodeficiency syndrome in whom pneumothorax developed from January 1985 to the present are reviewed. Spontaneous pneumothorax developed in 10 patients. All patients had a documented pulmonary infection. Four of 10 died, either of progressive respiratory failure or of concurrent infection. Patients with asymptomatic spontaneous pneumothorax can be safely observed. Patients with symptomatic pneumothorax should initially undergo tube thoracostomy. If an air leak persists, thoracotomy, stapling of blebs, and pleurodesis can be safely performed. Because of the prevalence of bilateral disease, a median sternotomy incision is recommended. Two patients underwent surgical treatment. Diffuse bullous disease associated with infiltration of lung parenchyma by Pneumocystis carinii pneumonia was identified in both. Both patients survived and were discharged. Patients whose pneumothorax developed while they were undergoing mechanical ventilation for respiratory failure induced by Pneumocystis carinii pneumonia had a 92.3% mortality rate. In all patients surviving for longer than 7 days after development of the initial pneumothorax, a contralateral pneumothorax later developed. Severe concurrent disease made the patients poor operative candidates. However, in the absence of concurrent illness, if a persistent large air leak is believed to contribute significantly to respiratory failure, surgical intervention may be indicated.