Hyperactivity of the vagus nerve and hypoactivity of the sympathetic nerves after VMH lesions both cooperatively contribute to the development of VMH obesity, mainly through hyperinsulinemia. Recently it has turned out that we should discriminate the role of the efferent vagus from that of the afferent vagus in the pancreatic hormone secretion. The hepatic branch is the main pathway of afferent fibers in the vagus, while the celiac (pancreatic) branch is the main pathway of efferent fibers. We investigated the role of the afferent and efferent vagus on the development of VMH obesity using the sectioning of the hepatic and celiac branch. Celiac vagotomy decreased insulin secretion and food intake, while hepatic vagotomy did not change them. The results suggested that the efferent vagus plays the main role in the development of VMH obesity, while the role of afferent vagus seems less apparent.