The absorption, distribution, metabolism, and excretion of 14C-benzo(f)quinoline (BQ), an air pollutant and component of cigarette smoke, was studied in male Fischer 344 rats. BQ was completely absorbed after oral exposure over a dose range from 1 to 100 mg/kg. Rats were treated iv with 1 mg/kg and total radioactivity was examined at sacrifice from 15 min to 3 days after dosing. BQ was rapidly distributed throughout the body and excreted in approximately equal amounts in the urine and via the bile into the feces. Metabolism to several compounds more polar than BQ occurred prior to excretion. Most of the radioactivity in blood and half of that in liver was due to metabolites of BQ, while only parent compound could be detected in other tissues. No parent BQ was present in the excreta. By 3 days after treatment, less than 2% of the 14C-BQ remained in the rats. Given the rapid metabolism and excretion of this compound it is unlikely that low dose, repeated exposure would result in its accumulation in the body.