Mice were injected with (14)C-toluene, and the radioactivity in the blood, exhaled air and organs was determinated liquid scintillation counter. The concentration of toluene in the blood attained a maximum 45 min. after the injection and decreased with a half life of 45 min. The amount of toluene in the exhaled air also attained a maximum 45 min. after the injection and decreased with a half life of 55 min. The exhalation curve of toluene paralleled the concentration curve of toluene in the blood. The ratio of the toluene concentration in red cells to that in plasma was 1:2.24. The concentration of toluene in the organs 180 min after the injection was in the decreasing order of adipose tissue > Kidney > liver > blood > brain. The fraction of the blood containing metabolite was applied to a thin layer plate and developed with toluene:acetic acid:water = 150:50:2.5. The radioactivity of benzoic and hippuric acids on the thin layer chromatogram of blood obtained 480 minutes after the injection was 83% and 17% of the total, respectively.