To investigate the effect of aclatonium napadisilate (Ac), a synthetic cholinergic compound, on human interdigestive gastrointestinal function, six healthy volunteers underwent gastrointestinal intubation for measurement of duodeno-jejunal motor activity and pancreatic enzyme secretion. Each subject was studied twice on two separate days and received either aclatonium (300 mg) or placebo intraduodenally in randomized order. Aclatonium significantly increased the overall length of the cycle of interdigestive motor complex (IMC) by a mean of 34% (p less than 0.05) without stimulating the phases of increased motor activity. Aclatonium slightly, but significantly increased output of lipase during phase II of the IMC (p less than 0.05), whereas outputs during phase I and III were not significantly changed. We conclude that aclatonium in a dose of 300 mg has only weak cholinergic effects on motility and exocrine pancreatic secretion in healthy humans during the interdigestive state.