Owing to limited endoscopy resources, various screening strategies for endoscopy have been proposed. Helicobacter pylori can be detected with high sensitivity and specificity by serology, and therefore we assessed the effects on diagnostic accuracy and endoscopic workload of a policy of screening clinic patients with dyspepsia before endoscopy by a strategy based on age, Helicobacter pylori serology, and use of non-steroidal anti-inflammatory drugs. 1153 patients were studied, of whom 842 were of known histological H pylori status (histology group) and 293 had serum assessed prospectively by in-house and commercial ELISAs for detection of IgG antibodies to H pylori. Overall, the screening strategy would have reduced endoscopy workload by 23.3% (95% confidence interval 20.9-25.8%) and would have had a sensitivity for detection of peptic ulcer of 97.4% (94.5-99.1%). No peptic ulcer or malignant disease was missed in the patients studied prospectively, but 6 of 192 peptic ulcers in the histology group would have been missed. A policy of screening young dyspeptic patients for H pylori by serology is more sensitive than symptom-based screening strategies, and may have an important role in reducing endoscopy workload.