The inhalational route of administration of freebase and crack cocaine exposes the lung to their combustion products, raising concern about possible adverse pulmonary effects. A brief historical review of cocaine and its methods of use precedes the presentation of data concerning current modes and patterns of use and some pulmonary complications of crack and freebase use. Results from a systematic study of a large sample of cocaine users document a high frequency of occurrence of acute respiratory symptoms in temporal association with cocaine smoking. No relationship was detected between the prevalence of acute pulmonary symptoms and identifiable aspects of techniques of cocaine administration. These results suggest that the respiratory consequences of alkaloidal cocaine are most likely attributable to the inhaled cocaine itself, rather than to variable characteristics of use. Table, references