Abstract: Objective 　To study the diagnostic value of Glycyl Proline Dipeptidyl Aminopeptidase ( GPDA), CA7-24 and CA50 in gastric cancer. Methods 　Serum levels of GPDA, CA7-24 and CA50 in 125 patients with gastric cancer, 77 patients with benign gastric tumor and 50 normal controls were measured by electro-chemiluminescence immuno-assay (ECLIA) and radioimmunoassay and automatic biochemical analyzer. Results 　Sensitivities of GPDA, CA7-24 and CA50 in gastric cancer group were 62. 4 %, 68. 0 % and 54. 4 %, respectively, and the specificities were 97. 6 %, 97. 6 % and 98. 4 %, respectively. The sensitivity of combined detection of three tumor markers increased to 89. 6 %, and the specificity was 93. 7 %. Conclusion 　GPDA, CA7-24 and CA50 can serve as the serum tumor marker in clinical diagnosis of gastric cancer. Combined detection of three kinds of serum tumor makers increases the detective positive rate.