This is a statistical observation of 285 cases of nasal allergic patients and 95 cases of allergic external otitis sensitive to house dust antigen et al. who visited my clinic during the period of November 1958 to October 1960. Also tested for sensitivity to house dust were 460 healthy male and female industrial workers and 209 healthy junior high school boys. 1) Among the 380 patients, 84% showed a positive reaction to a skin test with purified house dust. 2) Among 460 healthy workers who have been working from 5 to 10 years in the Taegu Monopoly Office Factory, 69% of A Group(100 workers who work in the dustiest environment), 22% of B Group(148 workers who work in a less dusty medium than A Group) and 13% of C Group(212 workers who work in the least dusty medium in the factory) showed a positive reaction to the 1/5.000 dilution of purified house dust. These results indicate that the dustier the environment becomes the more frequent positive reactions occur. 3) Only a 15% of 209 healthy junior high school boys showed positive reaction to the 1/5.000 dilution. 4) Inhalant antigens sensitive to Korean nasal allergic disease are in the following order : Silk(32%), Bacteria mixture(20%), Cotton(19%), Orris root(18%), Alternaria(14%), Cigarette smoke(13%) etc. 5) As a result of the study of 380 patients, Endo Purified House Dust is considered an important etiologic factor in allergic diagnosis and a most accurate test for sensitivity to house dust.