In 1918 Finsterer proposed that in cases of complicated duodenal and gastric ulcer, where the resection of the ulcerous part is very difficult by adherence to the surrounding tissues in high grade, the pylorus should be put out of use and the mucous membrane of the part of the remaining pylorus should be widely removed. In 1933 Fischer described on good results in similar cases, which were achieved by a new method based on his original idea, leaving always a part of pylorus and removing simply the mucous membrane of this part unto the pyloric ring. Suggested by this description, the author wanted to acertain whether or not there could be any possibility of secondary hamorrhage, perforation or suppuration of the part of stomach, remaining pylorus, ileum and jejunum, where the mucous membrane was removed, and to observe simultaneously the healing process, using dogs for experiments and following results were obtained. 1) The part of stomach or intestine where the mucous membrane and submucous muscular layer have been widely removed is coated with granulation at the beginning, which is later substituted by regenerating mucous membrane and never shows perforation or necrosis. 2) In the eliminating pylorus out of use if the mucous membrane and submucous muscular layer are removed unto the pyloric ring, the quick closure and adherence of the pylorus prevent the insufficiency of suture, cease the secretion of pyloric glands, put aside the irritation to the remaining ulcer by cessation of reflex movements of pyloric sphincter, prevent the hämorrhage and perforation and accelerate the healing of ulcer. 3) The removal of the mucous membrane and submucous muscular layer only from the intestine does not cause the perforation or necrosis of the concerning part of intestine. 4) The covering of the operated part of stomach and intestine with gastric omentum (omentum majus) makes the local adhesion of the abdominal cavity and prevents the suppuration and perforation.