OBJECTIVE:To discuss the effect of trastuzumab combined with chemotherapy on efficacy and serum tumor mark-ers in patients with human epidermal growth factor receptor 2(HER2)positive advanced gastric cancer. METHODS:74 advanced gastric cancer patients in HER2 positive were randomly divided into observation group and control group,37 cases in each group. Control group received cisplatin + capecitabine chemotherapy;based on it,observation group additionally received trastuzumab by intravenous infusion in the first day,8 mg/kg. 21 d was a course,and it lasted for 6 months. The short-term efficacy,long-term effi-cacy,serum tumor marker contents and toxic and side effects were compared between 2 groups. RESULTS:The effective rate (56.76% vs. 32.44%)and control rate(89.19% vs. 65.86%)in observation group were significantly higher than control group,the differences were statistically significant(P<0.05);progression-free survival time and median survival time in observation group sig-nificantly longer than control group,the differences were statistically significant(P<0.05);contents of serum carcinoembryonic anti-gen,carbohydrate antigen (CA)199,CA724 in observation group significantly lower than control group,the differences were statis-tically significant(P<0.05). And there were no significant differences in the incidences of nausea and vomiting,liver damage,bone marrow suppression and hand-foot syndrome in 2 groups (P>0.05). CONCLUSIONS:Trastuzumab combined with chemotherapy helps to reduce serum tumor markers content,and improve short-term efficacy,long-term efficacy of advanced gastric cancer patients with positive HER2.