Food hypersensitivity as a cause of abdominal symptoms was investigated by means of exclusion diets and double-blind food provocation in patients with irritable bowel syndrome. Twenty-seven patients entered the study; nineteen complied with dietary manipulation. Food hypersensitivity as a cause of their presenting symptoms was confirmed by double-blind food provocation in only three patients, who also had evidence of associated atopic disease and positive skin tests to common inhalant allergens. Evidence of minor psychiatric disorder was found in twelve of fourteen patients examined by an independent psychiatrist.