Abstract: To investigate the fragmentation mechanism of statins, six statins were studied by electrospray ionization-ion trap mass spectrometry (ESI-MSⁿ). Based on the forms of the main pharmacophore, the samples were analyzed into two groups. The first group, including simvastatin and lovastatin, which were detected in positive ion mode. It is indicated that most fragments are produced after neutral loss processes such as elimination of 18 u (H₂O), 28 u (CO) and 60 u (CH₃COOH) following the ring opening of the lactone. The second goup including pravastatin, atorvastatin, fluvastatin and rosuvastatin were invesgated in negative ion mode. It is observed that the main fragments are derived from neutral losses of 104 u (3-hydroxy-1,4-butyrolactone and H₂) and 160 u (3,5-dihydroxy-1,7-heptalactone) of pravastatin and atorvastatin. While losses of 62 u (CO₂ and H₂O) of fluvastatin and rosuvastatin are detected. And further losses of 42 u (CH₂=C=O) and 96 u (cyclohexen-3-one) are observed in MS³.These characteristics can be used for future structural analysis and identification in studies of statins and analogue compounds.