A simple analytical method for urinary phenol by high performance liquid chromatography was tested. This procedure consists of the following three steps: hydrolysis of urine with hydrochloric acid, extraction of phenols with isopropylether, separation and determination of phenol by high performance liquid chromatography, under the following operating conditions: column, LiChrosorb RP 18 (250 mm X 4 mm, I.D.); mobile phase, acetonitrile-water (3: 7, v/v) with a flow rate of 0.8 ml/min; column temperature, 40 degrees C; detection, UV monitor at 270 nm. The detection limit (signal-to-noise ratio = 2) was 1 ng. The analytical results by this method were compared with those obtained by another method used for gas chromatography. The analytical results obtained by the two methods were in good agreement (r = 0.998) for 30 normal urine samples tested. The geometrical average value for phenol in normal urine samples (n = 30) was 8.2 micrograms/ml. Therefore this method was proved to be useful for biological monitoring of benzene exposure.