OBJECTIVES To examine to what extent clinicians in Europe accepted the theory of the casual role of Helicobacter pylori (H.pylori) in duodenal ulcer disease in the year 1992, and to what extent the theory had influenced their diagnostic and therapeutic habits in the management of duodenal ulcer patients at that time. DESIGN Postal questionnaire. SETTING Three European countries: the UK, the Netherlands, and Denmark. SUBJECTS Three hundred and three gastroenterologists, 250 general practitioners, 83 junior hospital doctors. MAIN OUTCOME MEASURES Number of doctors believing H. pylori to be a significant cause of duodenal ulcer disease, use of diagnostic tests for detection of H. pylori and therapeutic regimens for eradicating H. pylori. RESULTS Four hundred and forty-two doctors replied. Eighty-four per cent of the British doctors, 73% of the Dutch doctors, and 47% of the Danish doctors accepted the role of H. pylori in duodenal ulcer disease. The rates were higher among gastroenterologists than among general practitioners. Eighty-four per cent of the British doctors, 80% of the Dutch doctors, and 48% of the Danish doctors used diagnostic tests for H. pylori, most frequently histological examination (64%). In patients with duodenal ulcer disease, H. pylori eradication was undertaken by 93% of the British doctors, 89% of the Dutch doctors, and 60% of the Danish doctors. A triple therapy (a bismuth salt, metronidazole, and either amoxicillin or tetracycline) was used by 57% (181/315) of the doctors. CONCLUSIONS H.pylori treatment is frequently used in some countries. However, the role of H. pylori in duodenal ulcer disease has not been accepted to the same extent in different European countries.