About Oui-Ga-Sil(胃家實) in order to considerate the contents recorded in Nai-Gyung Sang-Han-Lon and latter literature, definition, etiopathology, syndrome, differential diagnosis, therapy, Prognosis and prevention were classified. And the results were as follows: 1. Oui-Ga(胃家)was a term which indicated the whole digestive system such as stomach, small intestine, large intestine, rectum and anus. Sil(實)could be defined as the peculiar concept pertaining to the acute and last stage which was invaded to inside bowels because of abundance with evil influence. 2. Eliology of Oui-Ga-Sil was abunt gastric fever originally, injured mucus because of mistreatment, the invasion to inside of outside evil influence through meridian. Pathology was the opening and shutting appearance of gastric abundance with intestinal emptiness, and intestinal abundance with gastric emptiness, Oui-Ga-Sil could be occurred because of gastric abundant dryness and splenic humidifying capacity decrease. 3. Symptom of Oui-Ga-Sil was classified as for the sunlight outside syndrome and the inside abundant syndrome. The sunlight outside syndrome was body fever, sweating, no chilling, on the contrary hatred of fever. The chief complaint of inside abundant syndrome was daily fever, talking in delirium, hand and foot sweating, abdominal distention, difficult defection and those could be pertained to sunlight bowel syndrome. 4. Diagnostic views of Oui-Ga-Sil were that pulse was descending abundant large strong and smooth quick, a coated tongue was yellow, deep yellow, old yellow, thick, scorching dry rough or gray black. On abdominal diagnosis, pressing by hand, patient was conscious of pain, excessive pain, rejection against press, impossible press or intermittent abdominal pain and bowel cutting pain without press. 5. Differential diagnosis was that the sunlight of Nai-Gyung-Fever-Theory was outside desease making meridian the prime object, Baik-Ho-Tang syndrome was making figureless abundant fever the pivotal point. And important differential standard of splenic shrink syndrome was that a daily fever, an irritation with fever were not occurred. 6. Theory of Oui-Ga-Sil was that Seng-Gi-Tang classes had been used in attacking downward or making balance, and moxibustion on Jung-Wan, honey boiling induction theory had been also used. Attacking downward therapy was invigorating method to preserve mucus, and if mucus had been exausted with complicating emptiness prognosis had been appeared badly. 7. Preventing from Oui-Ga-Sil diet by rule, fitness to cold and warmth may be needed to prevent outside evil influence attack and inside evil influence occurrence. Prudence with being very busy, fatigue, wine and woman may be also needed not to be an injury to splanic and gastric spirit.