Eight Brown Norway rats were immunized twice at days 0 and 13 by intraperitneal injections of 10 micrograms Cry j I, one of major allergen to Japanese cedar pollinosis, mixed with 4.5 mg aluminium hydroxide gel. Serum level of Anti-Cry j I IgE antibody was detected by the method of ELISA. Mean value of serum levels of specific IgE to Cry j I in the sensitized rats was significantly higher than that in the non-sensitized five rats (p < 0.01). The grades of eosinophil and lymphocyte accumulation in the nasal mucosa of the sensitized rats were higher than those in the non-sensitized rats respectively (p < 0.05, p < 0.01). In the laryngeal mucosa, the grade of eosinophilia in the sensitized rats was higher than that in the control (p < 0.01), but no significant differences of lymphocyte accumulation in the larynx between the two groups were found. Only a small number of eosinophil and lymphocyte accumulations in the trachea of the both groups were observed and no significant differences of the grade of inflammatory cells accumulation between the two groups were found. According to the results of this fundamental study, allergic laryngitis in Japanese cedar pollinosis might be originated from Japanese cedar pollen.