Abstract:Polymerase chain reaction (PCR) is a useful method of detecting H. pylori from gastric juice, which can be obtained more safely and easily than gastric biopsies. We investigated the applicability of PCR assays of gastric juice aspirates to evaluate cure of H. pylori infection. Fifteen H. pylori positive patients with gastric ulcer or gastritis received anti H. pylori therapy. Four weeks after the cessation of treatment, endoscopy and the 13C‐urea breath test (13C‐UBT) were performed to evaluate the status of H. pylori infection. Gastric juice samples were collected and one biopsy specimen each was taken from the antrum and the body of the stomach. Results obtained from PCR of gastric juice aspirates were compared with those from PCR of gastric mucosae and 13C‐UBT. Fourteen of the 15 showed identical results. However, PCR assays of gastric juice aspirates were positive in one patient with negative results on the other two examinations. Restriction fragment length polymorphism of PCR products suggested that this discrepancy was due to detection of another strain passing through the stomach into the duodenum. Despite the detection of transient strains in gastric juice aspirates being infrequent, the results suggest the possibility of oral transmission of this org