Background. Well-devised studies comparing new but different monoclonal fecal tests for diagnosing Helicobacter pylori infection are scarce. The objective of this study was to compare the diagnostic accuracy of 3 monoclonal stool tests: 2 rapid in-office tools - RAPID Hp StAR and ImmunoCard STAT! HpSA - and an enzyme immunoassay test - Amplified IDEIA Hp StAR - for diagnosing H. pylori infection prior to eradication treatment. Methods. Diagnostic reliability was evaluated in 199 untreated consecutive patients with dyspeptic symptoms. The gold standard for diagnosing H. pylori infection was defined as the concordance of the rapid urease test, histopathology, and urea breath test. Readings of immunochromatographic tests were performed by 2 different observers. Sensitivity, specificity, positive and negative predictive values, and 95% confidence intervals were calculated. Sensitivity and specificity were compared using the McNemar test. Results. The sensitivity and specificity of Amplified IDEIA Hp StAR were 90% and 89%, respectively. This enzyme immunoassay test was significantly more sensitive than ImmunoCard STAT! HpSA and more specific than RAPID Hp StAR. The sensitivity and specificity of RAPID Hp StAR were 91% and 80%, respectively, according to observer 1, and 92% and 76%, respectively, according to observer 2. It was significantly more sensitive and less specific than ImmunoCard STAT! HpSA. The sensitivity and specificity of ImmunoCard STAT! HpSA were 69% and 90%, respectively, according to observer 1, and 74% and 89%, respectively, according to observer 2. Conclusions. Amplified IDEIA Hp StAR seems to be the most accurate stool test for diagnosing H. pylori for patients with dyspeptic symptoms. The currently available in-office tests obtain slightly less reliable results. © 2010 by the Infectious Diseases Society of Amenca. All rights reserved.