Our aim was to determine the role of the extrinsic and intrinsic nerves in the regulation of the small intestinal interdigestive myoelectric complex (IMC). In five dogs, the extrinsic nerves of the jejunoileum were divided, but the bowel was left in situ with its wall intact. After recovery, IMCs were detected in the duodenum (mean IMC period +/- SE = 188 +/- 19 min), from where most migrated distally into and through the jejunum (84%). In addition, extra IMCs appeared in the jejunum. Thus, the mean period of the IMCs in the jejunum (134 +/- 10 min) was shorter than in the duodenum (P less than 0.05). In contrast, after enteric transection and reanastomosis at the ligament of Treitz and at a site 75 cm distal to the ligament, fewer duodenal IMCs migrated into the jejunum (only 61%). However, extra IMCs still arose in the jejunum, so that the mean period of IMCs in the jejunum (111 +/- 5 min) was now similar to that in the duodenum (128 +/- 4 min, P greater than 0.05). Our data were consistent with the hypothesis that extrinsic nerves regulate the frequency of the small intestinal IMCs, while an intact enteric wall aids in their distal propagation.