A double-blind crossover trial of the alpha 2 agonist lidamidine hydrochloride in 72 patients with irritable bowel syndrome is reported. Lidamidine was found to have no significant effect on frequency and severity of abdominal pain or abdominal bloating. It did cause a statistically significant reduction in frequency of defaecation (P = 0.005), but this was of a degree unlikely to be of clinical importance. Although alpha 2 agonists inhibit gastrointestinal motility in animals this study suggests that lidamidine hydrochloride does not have a useful therapeutic role in irritable bowel syndrome.