Therapeutic drug monitoring using a new and faster high pressure liquid chromatographic (HPLC) method is discussed. Analysis of chloramphenicol and succinate esters and a large number of anticonvulsive drugs can be carried out using the same buffer and reverse-phase HPLC column by changing the solvent concentration to reflect the choice of drugs. A buffer prepared from 0.02 M sodium acetate and trifluoroacetic acid provides an optimal mobile phase for separation of a wide variety of drugs commonly used in pediatric medicine. Sample preparation and the use of special internal standards without extensive extractions provides excellent accuracy, reliability and sensitivity, and requires a minimum of preparation.