What is known and Objective: Helicobacter pylori eradication rates of currently accepted triple therapy regimens vary between geographic locations and do not exceed 70-80%. Eradication rates are much lower in locations where uncontrolled antibiotic use is common such as Turkey. In the present study, we aimed to test whether supplementing vitamins C and E to standard triple therapy, including a proton pump inhibitor plus amoxicillin plus clarithromycin, increased the H.pylori eradication rate. Methods: Two hundred patients infected with H.pylori were randomized into two groups in an open-label trial. In group A, patients (n = 160) were given standard triple therapy, including lansoprazole 30 mg BID plus amoxicillin 1000 mg BID plus clarithromycin 500 mg BID for 14 days, plus vitamin C 500 mg BID plus vitamin E 200 IU BID for 30 days. In group B, patients (n = 40) were given standard triple therapy for 14 days. The success of H.pylori eradication was defined as a negative 14C-urea breath test result, 4-6 weeks after the completion of therapy. Comaprisons were by both intention-to-treat (ITT) and per-protocol (PP) analysis. Results and Discussion: Two hundred patients (137 women, 63 men) were analysed using ITT analysis and 195 patients completed the study. In group A, H.pylori eradication was achieved in 132 of the 160 patients (82.5%) included in ITT analysis and 132 of the 157 patients (84%) included in PP analysis. In group B, H.pylori eradication was achieved in 18 of the 40 patients (45%) included in ITT analysis and 18 of the 38 patients (47.4%) included in PP analysis. Eradication rates were significantly higher in group A than in group B (P < 0.005). Eradication rates were not statistically significant between men and women in both groups. What is new and Conclusion: Adding vitamins C and E to standard triple therapy increases the eradication rate of H.pylori. Vitamins C and E may increase the eradication rate via increasing the effectiveness of the antibiotics by decreasing oxidative stress in the gastric mucosa and strengthening the immune system.