It is clear that immediate asthmatic response is mediated by IgE-dependent mechanisms. However, late asthmatic response is induced by inhalation of antigens without antigen specific IgE antibodies in some asthmatics, especially in intractable asthma induced by Candida antigen. To elucidate the relationship between those bronchial responses and antibodies, antigen specific IgG subclass antibodies in sera from asthmatics were measured and compared with IgE antibody. The results were as follows. 1. Avidin-biotin ELISA (enzyme-linked immunosorbent assay) method was established for the measurement of specific IgG and IgG subclass antibodies to mite or Candida antigen. 2. Serum levels of antigen specific IgG and IgG1 antibodies in asthmatics with LAR provoked by mite or Candida antigen were significantly higher than those in asthmatics without LAR (p less than 0.01). 3. Serum levels of specific IgE antibody to these antigens in asthmatics with LAR provoked by mite or Candida antigen were slightly lower than those in asthmatics without LAR, though the difference is not significant. These results suggest that high serum levels of specific IgG and IgG1 antibodies to these antigens play a role in inducing LAR in asthmatics with LAR.