Symptom scores, stool data, and the transit of a standard, solid meal were measured in 25 patients with irritable bowel syndrome during baseline conditions and after four weeks treatment with placebo and domperidone in the form of a double-blind cross-over trial. All patients had previously undergone a comprehensive series of diagnostic investigations and had failed to respond to dietary supplementation with coarse wheat bran (10-30 g daily). Compared with placebo treatment, domperidone had no significant effect on gastric emptying, small bowel or whole gut transit times, stool weight, frequency, or consistency. Most symptoms improved significantly with both placebo and domperidone treatments, compared with the baseline period, but there was no significant difference between placebo and domperidone for any of the symptoms. Abdominal distension, however, was reported on more days per week during domperidone treatment (p = 0.02). The findings in this study do not support the use of domperidone in the management of irritable bowel syndrome.