An increased seroprevalence of Helicobacter pylori (H. pylori) and especially of the high virulent cytotoxin-associated gene-A (CagA) positive strains has been found in several extragastroduodenal pathologies, characterized by activation of inflammatory mediators. Moreover, it has been reported that the risk of chronic bronchitis may be increased in H. pylori infected patients. The aim of the present study was to assess the seroprevalence of H. pylori and in particular of CagA-positive virulent strains in patients with chronic obstructive pulmonary disease (COPD). We evaluated 126 COPD patients (88 males and 38 females, aged 61.3+/-8.1 years) and 126, age and sex-matched, control subjects. All subjects enrolled underwent an enzyme-linked immunosorbent assay (ELISA) IgG serologic test for H. pylori and CagA protein. The prevalence of H. pylori infection in patients and controls was 77.8% and 54.7%, respectively (P<0.001) and that of CagA-positive H. pylori infection was 53.9% and 29.3%, respectively (P<0.001). Moreover, COPD patients had a significantly increased mean serum concentration of both anti-H. pylori IgG (118.3+/-24.4 vs. 61.9+/-12.9U/ml, P<0.001) and anti-CagA IgG antibodies (33.8+/-3.4 vs. 19.0+/-1.5U/ml, P<0.001). Finally, no statistically significant difference, as regards the spirometric values, was detected between H. pylori infected COPD patients and uninfected ones. In conclusion, H. pylori infection may be associated with COPD. Further studies should be undertaken to clarify the potential underlying pathogenetic mechanisms.