Abstract: Objective: To explore the diagnostic value of tumor marker (TM) biochip diagnostic system C12 in thediagnosis and monitoring of gastric cancer. Methods: Using the C12 diagnostic biochip system, we screened the serum of156 pathologically confirmed gastric cancer patients for 12 TMs including carcinoembryonic antigen (CEA), alpha-fetopro-tein (AFP), carbohydrate antigen 19-9(CA19-9), carbohydrate antigen 242(CA242), cancer antigen 15-3(CA15-3), cancerantigen 125 (CA125), prostate specific antigen (PSA), free-PSA, neuron-specific enolase (NSE), human chorionic go-nadotropin-beta(β -HCG), human growth hormone(HGH), and ferritin(Fe). The results were compared among different clin-ical stages of gastric cancer. Results: The overall sensitivity in these 156 patients of the C12 biochip system was 35.90%.The diagnostic rate of the C12 biochip system was 15.00% in stage Ⅰ patients, 25.00% in stage Ⅱ patients, 36.00% instage Ⅲ patients, and 47.73% in stage Ⅳ patients, with a statistical significance (contingency table chi-square test, χ² =7.81, P<0.05). Among the 12 TMs, CA19-9 had the highest sensitivity of up to 20.51%. With a diagnostic rate of 33.33%,the combined detection of CA19-9, CEA, CA125 and AFP was the most beneficial combination. Conclusion: The C12biochip diagnostic system is valuable for the diagnosis of gastric cancer, but its sensitivity for early stage gastric cancer isnot satisfactory. Optimizing these TMs and developing new and more effective biochip diagnostic systems are urgent.