Specific IgG4 antibodies were determined by enzyme-linked immunosorbent assay (ELISA), radio allergosorbent test (RAST), and s-CD23 in a total of 17 patients with nasal allergy who were given immunotherapy with house dust. The following results were obtained. 1) From the results between the serum antigen-specific IgG4 and the clinical effect of immunotherapy, there are many cases showing the elevation of antigen-specific IgG4 antibody titer. But in the elevated cases, there were only 7 cases showing good and excellent responses in a clinical effect of 41.1%. 2) IgG4 antibody was gradually elevated in many cases during immunotherapy, but in a few cases, abruptly increased after the maximum tolerated dose was established. 3) Regarding the outcome between IgG4 antibody and IgE antibody, cases of rising IgG4 and decreasing IgE occurred at a rate of 41%. 4) s-CD23 in sera gradually decreased in many cases during immunotherapy, but in a few cases, did not change.