Duodenal ulcer-promoting gene (dupA) was recently described as a new putative Helicobacter pylori virulence marker associated with an increased risk for duodenal ulcer and reduced risk for gastric carcinoma in Japan and Korea. Since differences regarding the association among H. pylori markers and H. pylori-associated diseases have been demonstrated around the world, we evaluated the presence of the gene in 482 strains from Brazilian children (34 with duodenal ulcer and 97 with gastritis) and adults (126 with duodenal ulcer, 144 with gastritis and 81 with gastric carcinoma) by PCR using the described primers and an additional set of primers based on Brazilian strain sequences. The results were confirmed by sequencing. The presence of cagA was investigated by PCR and also included in the analysis. dupA was present in 445 (92.32%) and absent in 29 (6.02%) strains. All samples from children with and without duodenal ulcer were dupA-positive (p=1.0). No association was observed among the strains from adults with gastritis (92.36%), duodenal ulcer (87.30%, p=0.30) and gastric carcinoma (87.65%, p=0.31). Conversely, cagA-positve status remained independently associated with duodenal ulcer (children: odds ratios (OR)=5.58, 95% confidence intervals (CI)=1.67-18.50; adults: OR=3.33, 95% CI=2.14-5.19) and gastric carcinoma (OR=6.58, 95% CI=3.51-12.30) in multivariate analyses. The presence of dupA was significantly higher in strains from children than in those from adults (p=0.01). In conclusion, dupA is highly frequent and not associated with H. pylori-associated diseases in both Brazilian adults and children, which points to regional differences in the distribution of the gene.