N-butylscopolamine is a generally accepted drug for the suppression of gut motility. Although it is used during routine ERCP, only few systematic studies have been carried out in patients to investigate its action on sphincter of Oddi motility. In the present study the effect of N-butylscopolamine on the motility of the sphincter of Oddi region has been evaluated in 17 patients undergoing routine diagnostic ERCP. The pressure parameters of these patients were compared with "normal values" obtained in 23 volunteers. A dose of 40 mg of N-butylscopolamine bromide (Buscopan) i.v. significantly reduced the contraction frequency of the sphincter of Oddi from 5.4 +/- 1.2/min to 1.0 +/- 1.4/min (p less than 0.001), the contraction amplitude from 106.3 +/- 27.8 mmHg to 55.2 +/- 23.5 (p less than 0.01) mmHg, and the basal sphincter of Oddi pressure from 13.9 +/- 3.0 mmHg to 11.0 +/- 3.5 mmHg (p less than 0.05), but had no effect on the pressure gradient between the common bile duct and the duodenum. These results clearly demonstrate that N-butylscopolamine inhibits contractions of the sphincter of Oddi, and may thus facilitate the intubation of the papilla.