Abstract: Objective:To investigate the significance of metronomic therapy against Helicobacter pylori (HP) in the prevention of delayed emesis caused by chemotherapy of gastric cancer compared with the routine therapy. Methods: HP infection was confirmed by carbon 14 breath test in 69 patients. Combined chemotherapy was employed for the first time in the patients, who were divided into groups A and B. Metronomic therapy was administered to group A ( n=33 ). Briefly, triplex medication against Helicobacter bacilli triplex was orally ad -ministered:20mg of omeprazole and0.5 g of amoxicillin twice daily, with 200 mg of tinidazole once daily. Oral administration in group A was performed for 14days from the start of chemotherapy. Simultaneously, 5-HT 3 antagonists were applied. By contrast, group B (n=36) was treated with the oral triplex medication against Helicobacter bacilli: 20mg of omeprazole and1 g of amoxicillin twice daily, with 400 mg of tinidazole once daily. Oral administration in group B was performed for7 days from the beginning of chemotherapy with simultaneous application of 5-HT 3 antagonists. Both groups were simultaneously treated with the5-HT 3 antagonist granisetron at 3 mg once daily during the administration of anti-HP therapy. HP infection was evaluated by immunohistochemistry before and after treatment. Results:The total effective rate for emesis in group A was 84.85%, which was significantly higher than that in group B (55.56%). Among the patients in group A, 15 .15 % demonstrated delayed emesis, compared with 44 .44 % of the patients in group B; the number of individuals was significantly lower in group A than in group B. The average number of chemotherapy cycles in group A was significantly higher than that in group B at 3.1 cycles; the difference between groups was statistically significant ( P<0.05). In addition, the HP infection in group B was significantly lower than that in group A ( P<0.05 ). Conclusion: Compared with one week of treatment with the conventional dose, two weeks of low-dose metronomic therapy against HP during chemotherapy can significantly reduce chemotherapy induced delayed emesis and can significantly reduce the degree of HP infection in patients with gastric cancer with HP infection.