Objective: To evaluate the contents of ? aminobutyric acid(GABA) and glutamate(Glu) in gastric cancer tissue and normal tissue surrounding the cancer. Methods: 30 patients of gastric cancer underwent surgical treatment were examined. A high performance liquid chromatographic method(HPLC) was applied for the analysis and quantification of GABA and Glu in gastric cancer tissues and normal tissues surrounding the lesion after precolumn derivatization with phenylisothyocyanate (PITC). GABA and Glu were determined with UV detector. The differences in GABA and Glu contents in gastric cancer tissues were regarded to have close link of lymph node metastasis and histological type. Results: GABA and Glu contents were high significantly in gastric cancer tissue comparing with those of surrounding normal tissue( P 0.05). Conclusion: GABA and Glu are involved in the factors of gastric carcinogenesis. The results suggest GABA Glu system detection should be included into the diagnosis and therapy consideration in gastric cancer.