Although it is debatable whether Helicobacter pylori may play a role in the pathogenesis of rosacea, some authors suggested that the treatment of H. pylori might have a beneficial effect. The aim of this investigation was to compare the prevalence of H. pylori between rosacea patients and controls, and to evaluate an effect of H. pylori eradication on rosecea by a 2-week triple therapy that was composed of amoxicillin, clarithromycin and omeprazole. H. pylori was detected by using gastroscopic biopsy with Warthin-Starry stain. Forty-two (84%) of 50 patients with rosacea and 39 (78%) of 50 controls had H. pylori, showing no significant difference in prevalence. The cure rates of H. pylori in rosacea patients and controls were 80% (16/20) and 85% (17/20), respectively. There was no significant decrease in the intensity of erythema in active treatment and placebo groups both during and after the treatment. Temporary improvement in papulopustules exclusively during the treatment (within 2 weeks) could be independent of H. pylori eradication. Overall, no significant reduction in the number of papulopustules was observed in active treatment and placebo groups after the treatment (in 2 months). Taken together, our study found no significant lessening of rosacea lesions by treating H. pylori infection, which conclusively does not concur with a view that H. pylori may be related to rosacea.