The use of 14C-urea breath testing for diagnosis of Helicobacter pylori infection in gastric mucosa has gained widespread acceptance and utilisation. We evaluated a 14C urea breath test (UBT) in 116 patients undergoing endoscopy. Seventy four patients were administered 185 kBq (5 mCi-conventional dose), and 42 patients reduced dose (92.5 IBq, 2.5 mCi) of 14C-urea. All were tested for H. pylori using culture, direct microscopy of gastric biopsies and histological evaluation of paraffin stained sections. Using the mean + three standard deviations as the cut-off value, a sensitivity of 96% and specificity of 100% was found for the conventional dose test. At reduced dose, sensitivity was 100% and specificity 96%. Positive and negative predictive values were 100% and 93% for the conventional dose test, and 96% and 100% for testing at reduced dose. We conclude that the UBT is a simple, non-invasive and useful diagnostic alternative for detection of H. pylori in infected patients. We advocate its use in patients less than 45 years of age without alarm symptoms, and also in cases where the need for endoscopic evaluation is not vital, such as after eradication therapy.