A high-pressure liquid chromatographic method was developed for chloramphenicol in plasma. Plasma samples were deproteinized with 2.5 volumes of acetonitrile, and the supernates were chromatographed on a reversed-phase column, using acidified ethanol-water as the mobile phase and UV spectrophotometry for detection. The sensitivity for accurate quantitation of chloramphenicol was about 2.5 microgram/ml in plasma, and concentrations as low as 0.5 microgram/ml could be detected. Only about 8 min is needed for each sample. This method is specific, rapid, and sufficiently sensitive and may be useful for clinical monitoring.