Excess secretion of goblet cell stimulated by inhalation anesthetics have side effects during operation or postoperative care. Mucosubstances, which are almost secreted by goblet cells in the epithelium of the respiratory tract, are secreted by a direct irritation of inhalation anesthetics. This study was carried out to compare the differences of mucus secretion on lower respiratory tract stimulated by ethyl ether, halothane and isoflurane. Total of 24 rabbits were used as experimental animals. The trachea and the 1st bronchi were fixed in 10% neutral buffered formalin. After embedding in paraffin, the specimens were sectioned to a thickness of 6 ${mu}{ extrm}{m}$, and PAS-H, Alcian blue pH 2.5 and Alcian blue pH 1.0 stains were performed for the observation of the composition and the quantity of the mucus. The results were as follows; Ethyl ether and isoflurane irritated the mucous membrane of the respiratory tract. Ethyl ether irritated more than isoflurane. Halothane irritated the mucous membrane, but its effect was minimal and had little influences during operation. In the specimens stained with PAS-H, Alcian blue pH 2.5 and Alcian blue pH 1.0, the mucosubstance lining the cilia and in the goblet cells of the trachea and 1st bronchi were the strongly PAS-H reactive mucosubstances, moderately Alcian blue pH 2.5 and Alcian blue pH 1.0. The PAS-H reactive mucosubstance were polysaccharides, neutral mucopolysaccharides, mucoproteins, glycoproteins and glycolipids. Trachea was easily affected than bronchi by inhalation anesthetics. Consequently, it is suggested that because halothane does not irritates respiratory mucosal secretion, its application may be efficient to the depressed respiratory system.