The interdigestive myoelectrical activity of the stomach and small bowel has been studied before and after celiac and superior mesenteric ganglionectomy in four healthy, well-trained conscious dogs. The interdigestive myoelectric complex was present before and after the gangliomectomy in all dogs, but variability in the duration of its cycles was increased by ganglionectomy. The percentage of time that action potential activity was present during the interdigestive period in the stomach and orad half of the small bowel was also increased in all animals after the ganglionectomy. The duration of phase III, the activity front, was unaltered by the operation, but the timing of the other phases became more variable after ganglionectomy. The time required for migration of the complex from duodenum to terminal ileum was more variable after ganglionectomy in the three animals in which it could be measured, and in two of them the migration time was shorter. An abnormal electrical pattern occurred in all animals after ganglionectomy. Its duration ranged from 0.5--5 min. Electrically, it appeared to represent an elongated, nonmigrating activity front.