Among a large group of users of illicit intravenous drugs, the incidence of bullous pulmonary damage was noted to be 2 percent (6/387). Bullous damage was significantly different in the drug users than in those who did not use drugs. The drug users were significantly younger than the nonusers, their bullae were large and confined to the upper lobes, and alpha 1-antitrypsin deficiency was very unlikely. These features strongly implicate intravenous drug abuse in the pathogenesis of these patients' bullous pulmonary damage.