In a double-blind multicentre trial to study the effect of pirenzepine in the treatment of non-ulcer dyspepsia, 104 of 128 patients, 52 in each of the study and control groups, completed the 4 weeks of the investigation. There was improvement of the endoscopic and clinical findings but no change of the degree of the mucosal inflammation or the extent of colonisation by campylobacter pylori. The mode of action of pirenzepine in patients with non-ulcer dyspepsia associated with campylobacter related gastroduodenitis remains obscure. Further studies are needed to investigate the possibility of a causal relationship between mucosal colonisation with campylobacter pylori and gastroduodenitis specially in cases of non-ulcer dyspepsia.