Metabolism of cyclohexanone was evaluated in groups of 5 young adult male Sprague-Dawley rats exposed by inhalation to the test article at time-weighted concentrations of 350 or 1479 ppm for 6 hours (determined by gas chromatography). The animals lost weight and exhibited sedation. The material was rapidly eliminated from the blood; concentrations of free cyclohexanone and cyclohexanol in the blood immediately after exposure were approximately 26.01 and 20.48 ug/ml, respectively, at the low-dose and 121.76 and 140.43, respectively, at the high-dose whereas only trace quantities of free cyclohexanol were observed at 24 hours. The total 72 h urinary excretion volumes of free cyclohexanone and cyclohexanol were 16.16 and 14.55 ug, respectively, at the low-dose and 142.93 and 264.08 ug, respectively, at the high-dose. By 72 hours, the excretion of conjugated cyclohexanol (primarily excreted during the first 24 hours) and a conjugated product tentatively identified as cyclohexanone occurred at levels of 13,306.15 and 546.69 ug, respectively, at the low-dose and 72,446.56 and 890.94 ug, respectively, at the high-dose.