BACKGROUND: Psychiatric disorders are health concern. The important issue is that the response of treatment of patients is different. Some patients are in remission, some suffer from adverse drug reactions (ADRs). Hepatic function is monitored by liver enzymes. It is important to detect liver injury and its evaluation according to the genetic polymorphisms in early phase of treatment. Alpha-glutathione-s-transfcrase (alpha-CiST) is a sensitive biomarker compared to the liver enzymes. GSTs are phase II conjugation enzymes that detoxify xenobiotic and protect cells from the oxidative stress. GSTMI, GSTT1 and GSTPI are polymorphic. Null genotypes cause lack of activity. Our aim was to investigate whether alpha-GST might be earlier biomarker than liver enzymes for liver injury and impact of individual susceptibility.