We established an IgE-capture ELISA for rat IgE antibody, and examined rat strain differences in the antibody responses against the major allergen of Japanese cedar pollen (Cry j I). First, IgE-capture ELISA and passive cutaneous anaphylaxis (PCA) method were compared. IgE-capture ELISA was found to be, in sensitivity, about 10 times higher than, and, in specificity, equal to, PCA. Second, seven strains of rat were immunized three times at days 0, 14 and 28 by intraperitoneal injections of 1 or 10 micrograms Cry j I mixed with 4 mg aluminium hydroxide gel. Anti-Cry j I IgE was detected by IgE-capture ELISA. Anti-Cry j I IgG and IgM responses were found not significantly different among different strains, but IgE responses in Brown-Norway (BN) rat were about 10 times higher than in other strains of rats. These results suggest that BN rat may be a useful animal model for studying physiological and pathological changes in the nose after pollen challenge to that organ.