In our previous study [Immunology 91 (1997) 161] using monoclonal antibodies (mAbs) specific to Cry j 1, a major allergen in Japanese cedar (Cryptomeria japonica) pollen, we identified five independent epitopes (EP-1-EP-5) on the molecule and found that EP-1 and EP-5 are the predominant allergic epitopes for humans and monkeys, respectively. In this study, we analyzed the epitopes recognized by IgE in the sera of 10 dogs sensitive to C. japonica pollen allergen using an IgE-ELISA inhibition method with these mAbs. The IgE reaction patterns varied among dogs. In eight of the 10 dogs, IgE recognized EP-5 which is a predominant allergic epitope for monkeys with the pollenosis. In four dogs, IgE recognized EP-1 which is a predominant allergic epitope for human patients with the pollenosis. In three dogs, IgE recognized EP-4 which is a heat-stable epitope. EP-5 is a predominant allergic epitope for dogs and some, but not all, dogs have IgE reaction patterns to the epitopes similar to those of humans.