This study attempted to determine whether the slow basic electrical rhythms of the antrum and the duodenum were related, and to search for relationships between the fast electrical activities of the two regions. Observations were made on five healthy, trained, unanesthetized dogs by means of detecting electrodes surgically implanted on the walls of the antrum and duodenum. No relationship was found, in either fasted or fed dogs, between the slow electrical rhythms of the antrum and duodenum. Feeding increased the fast activity in the antrum and in the duodenum, and under these circumstances, the fast activity in the duodenum was related to the slow basic electrical rhythm of the antrum.