Background : House dust mites have been known as the most important inhalant allergens in respiratory allergic diseases. By numerous in vivo and in vitro studies, Dermatophagoides farinae (D. farinae) and Dermatophagoides pteronyssinus (D. pteronyssinus) have been recognized as the most Important species among family Pyrogliphidae in Korea. Since environmental factors may have influences on the Pathogenesis of allergic diseases, studies using Korean house dust mites(HDM) for the immune and biologic reactions of HDM-sensitive allergic diseases are considered as significant. Materlals and Method : Thus we made in-house two Korean HDM(D. farinae and D. pteronyssinus) allergenic extracts and preformed the allergen standardization by in vitro methods and evaluated the reliabilitles of the clinical application. Result : There was 560μg and 680μg of proteins In 1㎎ of each lyophilized whole body extracts of D. farinae and D. pteronyssinus. In major allergen quantification using HDM specific monoclonal antibodies, there were 34.6μg Der f I and 17μg of Der f Ⅱ allergens 1㎎ of lyophilized D. pteronyssinus extract, and 21μg of Der p I and 18.6μg of Der p Ⅱ allergens in 1㎎ of lyophilized D. pteronyssinus extracts respectively. Evenly distributed many allergenic components including major allergens were identified in in-house HDM extracts by SDS-PAGE and immunoblot analysis. Both D. farinae and D. pteronyssinus were seen as does-dependent inhibition pattern by ELISA inhibition test. The amounts of allergen for the fifty percent inhibition were 0.19μg of D. farinae and 0.08μg of D.pteronyssinus Conclusion : As there were relatively large amounts of major allergens in in-house made HDM whole body extracts, we could make a conclusion that they had good allergenic activities. Thus it Is considered as clinically useful and reliable allergenic extracts.