Background: A number of noncommercial preparations of urease test have been described. The present prospective study evaluated the accuracy of one such preparation for the diagnosis of Helicobacter pylori infection. Methods: From February 1996 to November 1996, all patients undergoing elective upper endoscopy in a single endoscopy facility were included. Three antral biopsy specimens were taken. Two specimens were subjected to histologic examination, and one specimen was placed into a "locally made rapid urease test" (LRUT). Results of histologic examinations were taken as standards for comparison. The final result of LRUT was obtained on scrutiny of color changes at 4 hours after the start of the test. Results: Two thousand three hundred sixteen patients (male/female = 1.5:1) with a mean age of 56.7 +/- 0.4 years were included. Five hundred sixty-two patients (24.3%) had a history of eradication treatment for H. pylori. Nine hundred fifty-three patients (41.1%) were found to be positive for H. pylori on histologic examination. In patients in whom a history of eradication therapy was absent, the sensitivity, specificity, and positive and negative predictive values of the LRUT were 92.8%, 97.6%, 97.5%, and 93.0%, respectively. In patients with a history of eradication treatment, the corresponding figures were 76.1%, 99.6%, 96.2%, and 96.9%. Conclusions: The locally made rapid urease test provides a simple, safe, rapid, inexpensive, and accurate test for the diagnosis of H. pylori infection.