Background: A high prevalence of "Helicobacter pylori" infection has been reported among people with intellectual disability, especially those residing in hospital and similar settings. Surveys of inpatients have found unusually high rates of gastrointestinal malignancy, to which "H. pylori" infection predisposes. Methods: "Helicobacter pylori" antibody testing was arranged for all residents of five inpatient units for people with intellectual disability and challenging behaviour or psychiatric disorder. Eradication triple therapy was prescribed for those people with a positive result. [superscript 13]C urea breath testing was attempted after eradication therapy. Results: Thirty-seven residents were identified. It was possible to obtain blood for "H. pylori" antibody testing for 36 people. Twenty-two (59%) had a positive result. Dividing the people studied according to length of stay in hospital showed that 4 of the 18 people resident in hospital for less than 4 years (22%) had a positive antibody test, compared with 16 of the 19 people resident in hospital for greater than or equal to 4 years (84%; chi[superscript 2] = 14.6; P less than 0.001). Treatment led to eradication of "H. pylori" infection in 11 of the 12 people who were able to cooperate with testing. Conclusions: Clinicians should have a high index of suspicion for "H. pylori" infection among people with intellectual disability who have a history of institutional care or prolonged hospital admission, especially those who have spent more than 4 years in such settings. Testing for "H. pylori" antibodies is well tolerated. Eradication therapy offers many health benefits, including a reduction of the risk for stomach malignancies.