Background: A higher prevalence of Helicobacter pylori infection in rosacea patients than in healthy controls has been reported. Objective: The aim of this study was to investigate the effect of H pylori eradication therapy in patients with rosacea. Methods: Twenty-five rosacea patients and 87 age- and sex-matched healthy controls were included in this study. We detected IgG and IgA antibodies against H pylori in both groups. An upper gastrointestinal endoscopy and a rapid urease test were performed on the 13 patients with rosacea who accepted this procedure. Amoxicillin 500 mg 3 times daily, metronidazole 500 mg 3 times daily, and bismuth subcitrate 300 mg 4 times daily were administered to patients positive for H pylori . The severity of rosacea was scored before and after treatment. Results: There was no statistical difference in seropositivity in either group. In H pylori –positive rosacea patients there was a significant decrease in the severity of rosacea at the end of the treatment as compared with the initial scores. Conclusion: Our findings suggest that H pylori may be involved in rosacea and that eradication treatment may be beneficial. (J Am Acad Dermatol 1999;40:433-5.)