The main purpose of this work is the study on the etiology and pathology of the anorexia in oriental and western medicine. An appetite is stimulated by the need of supply of nutrition for life and the physical desire of hunger which appeared as the alternative of taste. In this paper, I investigated the anatomical and the physiological function system, the Piwei functional system and meridian distribution, and the differentiation of the disease according to the Zangfu(internal organs) in association with the anorexia. And conclusion could be summarized as follows : 1. The tongue, one of the Piwei functional system(脾胃機能系), is connected with Pi(脾), Xin(心), Gan(肝) and Shen(腎) meridian. Especially Pi and Xin meridian have the close relations with taste. 2. The appetite has the close relations with Piwei. The appetite and digestion is influenced by the function of smoothing and regulating and bloodflow of Ki(肝主疏泄), warming the Shen to activate the function of Pi(腎主溫養), cleansing the inspired air and keeping the Ki flowing downward(肺主肅降). 3. The cause of anorexia is the insufficiency of Ki of Piwei(脾胃氣虛), the attack of Wei by hyperactive Gan Ki(脾氣犯胃), the insufficiency of Wei Yin(胃陰不足), the declination of the fire from the vital gate(命門火衰) and the retention or stagnancy of undigested food (飮食停滯). Especially, the main cause of anorexia is the insufficiency of Ki of the Piwei(脾胃氣虛). 4. Recently the attack of Wei by hyperactive Gan Ki(脾氣犯胃) is raised by the main cause of anorexia. 5. The mental function of anorexia, which is induced by the unbalance of Pi, is directly associated with Xin(心) and Xin meridia(心經). 6. The goal of the treatment of the anorexia is dependent on the recovery of the weakness of the Pi. And for this goal, the disorders of the other organs is also treated. 7. In the point of the anatomy and physiology, the main cause of anorexia is the loss of function of the autonomic nerve system and the vagus nerve.