Glutathione S-Tanaferase (GST) is tripeptide, which plays a central role in the detoxification of electrophilic xenobioticas, including cytotoxic drugs and carcinogens, by conjugation with redueed glutathione. There are four major claases af human GST : pi, alpha, mu and rnicrosomal, They are propoaed as a marker for human and experimental neoplasia iincluding liver, kidney, lung,colon, uterine cervix, etc. Expression of pi, alphn, mu form of GST in control (15 cases), CIN (14 cases), invasive carcinoma (28 cases) of human uterine cervix was investigated immunohistochemically. They were selected fram September, 1992, to,June, 1992, in the department of Obstetrics and Gynecology, Yonsei university College of medicine. In nucleus, the expresaion of GST pi was increased statistically significant in case of CIN and invasive Ca. of Cx. compared to control(p=0.018, p=0.002). But expression of GST alpha, mu has no significant difference in each case. In cytoplasms, the expvession of GST pi was increased statistically significani, in case of CIN and invasive Ca. of Cx. (p=0.001, p<0.001). But expreasion of GST alpha, mu has no significant differenrce in each case. There was no statistically significant diHerence in expression of GST isoenzymes oC each nucleua and cytoplasm according to stage and cell type in Ca. oC Cx. The further evaluation of survival and expression of GST pi in Ca. of Cx. in order to establish new prognostic factor in Ca. of Cx.