Abstract Pulmonary alveolar macrophages (PAMs) obtained by bronchopulmonary lavage from 6 normal non-smoking volunteers were incubated with [ 3H]-benzo[ a]pyrene to ascertain the normal metabolism and conjugation of polycyclic aromatic hydrocarbons. Through the use of a crude glucuronidase preparation, both glucuronic acid and sulfate conjugates were examined. Phenols and quinones were identified by high-pressure liquid chromatography as the principal free metabolites formed during 1 h incubation with benzanthracene induced PAMs. In addition, phenols and quinones were major substrates utilized by these cells for conjugation during the incubation period. The ranges of benzo[ a]pyrene metabolites produced by PAMs from non-smokers were compiled and the variation in production as well as detoxification of proximate carcinogenic benzo[ a]pyrene metabolites are presented.