It is becoming increasingly clear that obstructive airway disease and early emphysema occur in some drug addicts who intravenously abuse drugs intended for oral use. We report four patients with such a history who had clinical, pathophysiologic, and radiologic evidence of severe obstructive airway disease with hyperinflation. Three patients had bullae. All had radiologic changes of intravenous talc granulomatosis. One patient had moderately severe emphysema at autopsy. The pathogenesis of this disease is uncertain but may involve synergism with cigarette smoke, direct toxic effects of the drug, or induced intravascular leukocyte sequestration causing proteolytic pulmonary injury.