After organic disease had been excluded as far as possible by clinical examination, including laboratory tests, analysis of faeces, and X-ray examination or endoscopy of the upper and lower gastrointestinal tract, 61 patients were given either 50 mg trimipramine at bedtime or identically looking coded placebo in a prospective study for 4 weeks. The complaints were graded on an analogue scale by both the patients and the physicians. The results showed that the complaint scores were significantly reduced to about half in the placebo group. In the group treated with trimipramine a significantly greater reduction was found for the scores of vomiting, sleeplessness, depression, and for the mucus content of stools. The scores for tiredness during treatment had decreased less in the group receiving trimipramine than in the one receiving placebo. These improvements occurred already during the first week of treatment. No adverse side effect was recorded.