The sera from 25 patients with clinical type I allergy against dogs were investigated by means of immunoblotting, using extracts of dog hair/dander, skin, hair, saliva, salivary gland, serum and liver. 96% of the patients' sera showed IgE antibodies reactive with 19- and 23-kilodalton (kDa) proteins in the hair/dander extract. The 23-kDa IgE-binding protein was preferentially detected in the hair extract and saliva but not in skin, salivary gland, serum and liver extracts. The 19-kDa band was strongly expressed in skin, but not in hair, serum and liver. Inhibition experiments using the 23-kDa containing extract prepared from hair and the 19-kDa containing extract prepared from skin revealed that these two proteins are likely to be immunologically independent allergens.