Lung histopathology was reviewed from 52 autopsies with positive toxicologic tests for cocaine from the medical examiners' offices in Dallas and Austin, TX. The median patient age was 34.7 years, and the male to female ratio was 2:1. Twelve individuals primarily used the drug intravenously and six primarily smoked it, but in most patients usage history was not known. The most frequent manner of death was accidental, consisting predominantly of cocaine overdoses. Other frequent manners of death included both natural causes and homicides. Subjects with chest trauma were excluded from the study. Twenty-three age-matched control cases with negative cocaine histories and toxicologic tests also were obtained from medical examiner autopsies. Histopathologic findings in the cocaine abuse group included acute hemorrhage, 58% (P = .05); chronic hemorrhage, 40% (P < .01), interstitial pneumonitis/fibrosis, 38% (P < 0.01); congestion, 88% (P < .01); and intra-alveolar edema, 77% (P < .01). These changes were remarkably consistent regardless of locale or method of use. Our findings demonstrate that pulmonary hemorrhage is more frequent than suggested by clinical hemoptysis and that chronic pulmonary diseases such as interstitial fibrosis may develop in long-term users.