Abstract: Objective To study the clinical significance of glutathione-s-trannsferase(GST-π)expression in gastric carcinoma with peritoneal metastasis.Methods The GST-π protein expression of resected speciments from 56 cases of primary gastric cancer with peritoneal metastasis and 24 peritoneal metastasis in contrast with 40 cases of primary gastric cancer without peritoneal metastasis were detected by immunohistochemistry,and their clinical data were also investigated.Results The positive GST-π expression rate in paratumor normal tissues,in primary gastric cancer without peritoneal metastasis,in primary gastric cancer with peritoneal metastasis and peritoneal metastasis was 30.0%(6/20),72.5%(29/40),89.3%(50/56),66.7%(16/24),respectively.The positive GST-π expression rate in group without peritoneal metastasis was lower than that in group with peritoneal metastasis.The difference was statistically significant.The positive GST-π expression rate in peritoneal metastasis was lower than that in primary gastric cancer.The GST-π protein expression was correlated with the histology type of the patients with peritoneal metastasis(P＞0.05),but not related to age,sex,organ infiltration,Borrmann types,serous infiltration,lymph node metastasis and peritoneal metastasis(P＜0.05).Kaplan-Meier survival statistical Results showed that the high expression of GST-π of the patients with peritoneal metastasis was related to the life span(P＞0.05).Conclusion The expression of GST-π had correlation with the histological category of primary gastric cancer with peritoneal metastasis.The determination of GST-π expression by immunohistochemistry may be useful for the estimation of prognosis and the establishment of chemical therapy regimen for gastric carcinoma patients with peritoneal metastasis.The high expression of GST-π in gastric carcinoma may have correlation with the incidence of peritoneal metastasis.