Gas chromatographic methods have been developed using a Supelco 1240-DA column for the determination of pentachlorophenol (PCP) in plasma and urine samples, and phenol in urine samples. These methods required no derivatization. Electron capture detection has been used for PCP determination, while flame ionization detection has been used to determine urinary phenol. The proposed phenol method avoids the use of perchloric acid, a safety hazard, as well as the formation of interfering compounds, which may be read as phenol if column resolution is inadequate.