Increased expression of the glutathione Stransferase (GST: E, C, 2, 5, 1, 18) π class isoenzyme is associated with both tumor and preneoplastic tissues. In order to further characterize the alteration of GST-π gene expression during progression of carcinoma, both the levels of GST-π DNA in one normal gastric tissue and 20 gastric tumor with perineo-plastic normal tissue，and the GST-π RNA in the normal gastric tissue and 12 gastric poorly differiented adenoearcinomas with corresponding perineoplastic normal tissues were tested using Dig-GST-π cDNA probe by Dot blot hybridization.No significant change of GST-π DNA level, but the expression level of GST-π RNA in 6 of eight gastric tumors was higher than in normal gastric tissue，and in 7 perineoplastic normal tissue of twelve poorly differentiated adenocarcinoma was higher than that in its corresponding tumor. This suggests that the elevation of GST-π gene expression is related to gastric tumor, and earlier than the changes of cell morphology.