Helicobacter pylori, the most important cause of gastritis and peptic ulcer, recently has been associated with several extradigestive diseases. The aim of this study was to assess the prevalence of Helicobacter pylori infection and the effects of bacterium eradication in 42 consecutive patients affected by idiopathic chronic urticaria. Helicobacter pylori was assessed by [13C]urea breath test. Amoxicillin, clarithromycin, and lansoprazole were given to infected patients for seven days. Urticaria and gastrointestinal symptoms were assessed on enrollment and after eradication. Fifty-five percent of patients proved to be infected by Helicobacter pylori. Prevalence of gastrointestinal symptoms did not differ between infected and uninfected patients. Eighty-eight percent of infected patients in whom the bacterium was eradicated after therapy showed a total or partial remission of urticaria symptoms. Conversely, symptoms remained unchanged in all uninfected patients. In conclusion, Helicobacter pylori affects a high percentage of patients with idiopathic chronic urticaria; however, typical gastrointestinal symptoms do not identify infection status. Bacterium eradication is associated with a remission of urticaria symptoms, suggesting a possible role of Helicobacter pylori in the pathogenesis of this skin disorder.