Using 5 conscious mongrel dogs, a study was conducted to investigate the vagotomy on gastroduodenal movements. At the first operation, the electrodes and strangage force transducers were attached to the antrum and duodenum; after making an electromyogram and recording contraction waves simultaneously, a transthoracic truncal vagotomy (TV) was performed and similar recordings were done. In order to evaluate the effect of TV on antral motility as well as antroduodenal coordination, the motility of the antrum and average contraction force per time unit were measured before and after TV. Furthermore induced inhibition and propagated excitation were analyzed referring to lag cross correlations before and after TV. The results were as follows: As compared with pre-vagotomy values, the post-vagotomy measured amount of motility as well as the average contraction force were reduced. Before TV in digestive state both propagated excitation and induced inhibition could be recognized. During phase II in digestive state only propagated excitation could be demonstrated, while in phase III both were absent. After TV in digestive state propagated excitation was noted, but the propagating time was shorter than before TV. Induced inhibition could not be demonstrated any longer. Furthermore, during phases II and III in the interdigestive state both were not noted.