Objective To explore the expression of glutathione-S-transferase-π(GST-π),P-glycoprotein (P-gp),topoisomerase Ⅱ (Topo Ⅱ) and thymidylate synthase (TS) in gastric adenocarcinoma tissues and the clinical significance.Methods Envision method of immunohistochemistry was used to detect the expression of GST-π,P-gp,Topo Ⅱ and TS in sample of 64 gastric adenocarcinoma tissues and 12 normal gastric mucosas,and their corresponding clinical data were comprehensive analyzed.Results The expression positive rates of GST-π,P-gp,Topo Ⅱand TS were respectively 76.6 ％(49/64),64.1％ (41/64),84.4 ％ (50/64) and 53.1％ (34/64),that were all higher than in gastric mucosa [8.3 ％ (1/12),8.3 ％(1/12),16.7 ％ (2/12),0],the differences were statistically significant respectively (P ＜ 0.01).Their positive expression rates were closely relevant to the degree of differentiation (P ＜ 0.05),but not to the patients' gender,age,tumour size,clinical staging,invasive depth and lymph node metastasis (P ＞ 0.05).The expressions of GST-π,P-gp and TS in high and middle differentiation adenocarcinoma were high.er than in low differentiation,but the expression of Topo Ⅱ in high and middle differentiation adenocarcinoma was lower than in low differentiation (P ＜ 0.05).Conclusion GST-π,P-gp,Topo Ⅱ and TS are over-expressed in gastric adenocarcinoma,which is related to the multidrug resistance of gastric adenocarcinoma.The joint detection of the expression of GST-π,P-gp,Topo Ⅱ and TS in gastric adenocarcinoma can be looked as an important symbol for guiding its chemotherapy drug and prognosis.