This study examined the prevalence of Helicobacter infection in the pyloric mucosa of pigs and its histopathological and molecular characteristics. Forty porcine pyloric samples were examined for Helicobacter infection by silver staining and PCR assay. The PCR product (376 bp) was digested with NdeII to differentiate between Helicobacter heilmannii and Helicobacter pylori. Another PCR assay run to produce an 1157 bp fragment was performed using a primer set designed from the 16S rRNA gene of Candidatus H. suis, and its product was cloned and sequenced. Infection rates were 62.5% (25/40) and 95.0% (38/40) as determined by silver staining and the PCR assay, respectively. On histopathological examination, lymphoid follicle aggregation in the pyloric mucosa and granulocytic migration into the lumen of pyloric glands were observed in 24 (60.0%) and 33 (82.5%) gastric samples, respectively. All PCR products, except that of H. pylori, were cut into two fragments of 147 and 229 bp by enzymatic digestion with NdeII. Sequencing of the 16S rRNA gene showed that the bacterium had 99.57% (1152 bp/1157 bp) homology to the 16S rRNA gene of Candidatus H. suis.