The histopathologic changes in the nasal and bronchial mucosa were well studied in the allergic rhinitis and asthma. When the airway is sensitized in an individual with allergy, the tracheal mucosa could also be sensitized and get the hitopathologic changes. But the studies on the tracheal mucosa are lacking. The present study was made with the aims of observing these changes in the tracheal mucosa of guinea pigs with experimentally induced airway allergy and presenting the basic data for further studies. Nineteen guinea pigs were used as allergy group and sixteen guinea pigs were used as control group. The peripheral blood and tracheal mucosa were obtained and examined by light microscopy. The results were as follows ; 1) The number of the peripheral blood eosinophils was a little larger in the allergy group than in the control group but there was no significant difference between two groups. 2) The number of the eosinophils and goblet cells in the tracheal mucosa were significantly larger in allergy group than in control group. But there was no significant difference in the number of the mast cells between two group. 3) The epithelial loss of the tracheal mucosa was significantly more severe in allergy group than in control group. Based on the results, it was concluded that the histopathologic changes compatible to the allergy was observed in the tracheal mucosa of guinea pigs with experimentally induced airway allergy. It suggested that the tracheal mucosa could play the role of a shock organ in allergic condition and cause clinical symptoms besides the nasal or bronchial mucosa.