In order to elucidate the pathogenesis of achalasia, adult mongrel dogs were used for experimental research on the blood flow to the esophagus following bilateral cervical vagotomy. The control group consisted of forty dogs which were subjected to acute experiment. Thirty dogs were sacrificed for induced-achalasia-like animal. However only seven of them were eligible for this study. The measurement of the blood flow was taken from two sites of the esophagus by using the thermoelectrical method, the upper one was located at 2 cm distal to V. hemiazygos, the lower one 2 cm proximal to the esophageal hiatus of the diaphragm. The following conclusions were obtained. 1. On adrenaline loading, an increasing blood flow to the esophagus was observed in the control group. 2. A decreasing blood flow was demonstrated in the achalasia-like group. 3. The disagreement of the above two measurements could be abolished on administration of an alpha blocking agent; phentolamine. Accordingly, a decreasing blood flow to the esophagus on adrenaline loading in achalasia-like group in contrast to the control one greatly suggested that the abnormality of the blood flow to the esophagus might predispose to the pathogenesis of the achalasia.