The influence of the proximal selective vagotomy (PSV) with mobilisation of the esophagus of 6 cm or up to the upper thorax apertura on esophageal motility in a first group and mobilisation of 2 or 7 cm on the lower esophageal sphincter tone in a second group was investigated in canine experiments. The loss of coordinated peristalsis in the denuded segment causes a deterioration of esophageal passage. The degree of disturbance of swallowing depends on the length of the mobilisation. Reduction of lower esophageal pressure was observed. These reduction was not influenced by the extent of this motilisation. Acid reflux was not seen. Due to anatomical differences between these two species, these results cannot be readely transferred to human. Enlarged mobilisation of the esophagus for completion of PSV cannot be recommanded without reservation. Clinical studies are needed.