IgG antibody reponses to house dust mite is known to be detected in sera from mite sensitive asthmatics and even in sera from specific IgE negative healthy controls and non atopic asthmatics. To evaluate the IgG subclass response to house dust mite(D. farinae) in specific IgE positive or negative asthmatics and controls, we examined the IgE and IgG subclass responses to D. farinae whole body extracts by immunoblot analysis in 20 sera from 5 D. farinae-specific IgE positive asthrnatics and 5 atopic controls and 5 non atopic asthmatics and 5 non atopic healthy controls. IgE antibodies in sera from D. farinae-specific IgE positive asthmatics bound to 17 protein bands of D. farinae(164, 127, 98, 94, 86, 80, 70, 61, 51, 41, 30, 23(Der f I ), 19, 17(Der f II), 15, 13, 11 KD). IgG1, IgG2, IgG3 and IgG4 antibodies bound to 13, 9, 7, 13 protein bands of D. farinae, mainly protein bands with molecular weight 30 to 164 KD, and there were no differences in binding patterns between asthmatics and controls regardless of the presence of specific IgE ant,ibodies. In conclusion IgG subclass antibody responses to D. fcrinoe from sera of asthmatic patients and controls were seemed to be restricted to high molecular weight proteins from 30 to 164 KD rather than to Der f I and Der f II regardless of the presence of IgE.