Background: Helicobacter pylori (H. pylori) is important cause of peptic ulcer and gastric cancer. Moxifloxacin is effective antibiotic for treatment for H. pylori. However, there were limited studies as first line therapy. Probiotics had been shown to decrease therapy-related side-effect and increase eradication rate. Aim of this study was to evaluate the efficacy of moxifloxacin-dexlansoprazole based triple therapy with probiotic for H. pylori treatment in Thailand. Methods: Patients with H. pylori infected gastritis were randomized to receive 7- or 14-day moxifloxacin-dexlansoprazole based triple therapy with probiotic or placebo. Regimen consisted of 60 mg dexlansoprazole twice daily, 400mg moxifloxacin once daily, 1g clarithromycin MR once daily. Probiotic used in this study was 282.5mg Saccharomyces boulardii (S. boulardii) in capsule prescribed twice daily. CYP2C19 genotyping, antibiotic susceptibility tests, and CagA genotyping were also done. Successful eradication was defined as a negative 13C-urea breath test at least 4 weeks after treatment. Results: Total of 108 subjects was enrolled (27 each to 7-and 14-day regimens with probiotic or placebo). Antibiotic susceptibility tests showed 29% fluoroquinolone, 19% metronidazole and 4% clarithromycin resistance. CYP2C19 genotyping demonstrated 43%, 47% and 11% were rapid, intermediate and poor metabolizers, respectively. CagA genes were positive in all patients. Eradication rates of 7-day and 14-day regimens with probiotic were 100%, and 93% respectively. There were no significant differences between eradication rate of 7-day and 14-day regimen with or without probiotics. Regarding side-effects, incidence of nausea, abdominal discomfort, bitter taste, and diarrhea were significantly lower in regimen with probiotic group compared with placebo(7.4%vs. 22.2%; p=0.028, 0.00%vs.14.8%; p=0.003, 35.2%vs.70.4%; p=0.0002, and 0.00%vs.9.3%; p=0.028, respectively). Conclusions: 7-day moxifloxacin-dexlansoprazole therapy plus S. boulardii provide an reliable cure rate of H. pylori in non-ulcer dyspeptic patients in Thailand, independent of CYP2C19 genotype. Probiotic adding also decreased side effects during the treatment.