An association between (unculturable) gastrospirillum-like organisms (GLO) and ulcerative lesions in the pars oesophagea in stomachs of swine has been claimed. In dogs GLO detected by microscopy may represent several Helicobacter species or subspecies. Therefore we investigated which Helicobacter spp. are present in stomachs of swine and their possible association with ulcerative lesions of the pars oesophagea. The presence of Helicobacter spp. in the antrum and pars oesophagea in 122 stomachs of slaughter swine was determined by microscopy (n = 122), by culture on selective and nonselective media (n = 112), and by a genus-specific 16S ribosomal DNA (rDNA) PCR (n = 80). GLO could not be cultured. Phylogenetic analysis of 43 16S rDNA fragments (out of 54 PCR-positive biopsy specimens) revealed the presence of Helicobacter heilmannii type 1 in 42 of them. This correlated with the presence of bacteria with GLO morphology. Helicobacter bilis 16S rDNA was amplified directly from one sample harboring bacteria with H. bilis morphology. The association between Helicobacter spp. and gastric lesions was investigated with a second group of 41 pigs with (n = 21 cases) or without (n = 20 controls) gastric lesions. Fifteen of the 21 cases were positive by PCR or microscopy, compared to 7 of 20 of the controls (P = 0.03). 16S rDNA sequence analysis of 7 of 14 PCR-positive cases revealed the presence of H. heilmannii type 1. Microscopy showed bacteria with GLO morphology. One sample (cases) was culture negative but PCR positive for Helicobacter pullorum-related 16S rDNA. In conclusion, our findings indicate that H. heilmannii type 1 is the predominant Helicobacter spp. in the stomachs of pigs and that its presence is associated with ulcerative lesions in the pars oesophagea.