BACKGROUND/AIMS: In this study we assessed the accuracy of the Helicobacter pylori (H. pylori) stool antigen (HpSA) test for the diagnosis of H. pylori infection in Korean adults. METHODS: Eighty-three patients were included in this study. They all underwent gastric endoscopy and biopsy. Biopsy specimens were taken from the antrum and body. The rapid urea test and pathologic findings showed that 46 patients were H. pylori-positive and 37 patients were H. pylori-negative. A stool specimen was collected from each patient and tested using a HpSA kit. RESULTS: When a cut-off value of 0.16 was adopted according to manufacturer's recommendations, the sensitivity, specificity, positive and negative predictive value, and accuracy of HpSA test were 100%, 81.1%, 86.8%, 100%, and 93.2%, respectively. However, when a cut-off value of 0.332 was adopted on the basis of our receiver operation characteristics curve, the sensitivity, specificity, positive and negative predictive value, and accuracy of HpSA were improved as 100%, 97.3%, 97.9%, 100%, and 98.8%, respectively. CONCLUSIONS: The HpSA test is a highly reliable diagnostic method for H. pylori infection.