Published analytical methods for the quantitative determinations of presently available five 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors ("statins"), lovastatin, simvastatin, pravastatin, fluvastatin and atorvastatin, are reviewed for therapeutic drug monitoring purpose in patients. Almost all assay reviewed are based on hi h-performance liquid chromatography or gas chromatography. Some purification steps (liquid-liquid extraction, solid-phase extraction, etc.) have been used before they are submitted to separation by chromatographic procedures and they are detected by various detection methods like UV. fluorescence and mass spectrometry. This review shows that most method may be used quantitative determination of statins in plasma and they are suitable for therapeutic drug monitoring purpose of these drugs. (C) 2003 Elsevier B.V. All rights reserved.