Von priquet(1906) once said 'The vaccinated person behaves…… in a different manner from the person who has not previously been in contact with such an agent. Yet he is not insensitive to it. We can only say of him that his power to react has undergone a change. For this general concept of changed reactivity I propose the term allergy……'. Many investigators have devoted themselves to finding the pathophysiology, diagnosis and treatment of allergy. To determine the causative allergen and pathologic changes, ninety six persons suspected of nasal allergy had been surveyed. They had been out patients who visited Hanyang University Hospital from January, 1981 to September, 1981. These patients had complete history taking, anterior rhinoscopy, laboratory tests including eosinophil count, intradermal skin test an X-ray study of paranasal sinuses. Then the patients who had positive results from the tests were treated with hyposensitization using allergen manufactured by Torii phamaceuticals. The following summary gives the results of this study : 1) The most probable age incidence for male is 11-20 and for females 31-40 years. 2) Predominant symptoms were watery nasal discharge, nasal stuffiness and itching sensation in nasal cavity with sneezing in over 85%. 3) Seasonal predominance was not observed and in over 30% the allergic symptoms sustained throughout the year. 4) The colors of nasal turbinates were pale in 68%, normal in 16% and others in 16%. 5) The nasal discharge was watery in 72%, mucoid in 26% and mucopurulent in 2%. 6) X-ray study of paranasal sinuses demonstrated no pathologic changes in 67% and abnormal findings in 33%. 7) In nasal eosinophil smear, increased eosinophil have been observed in over 79% in our nasal eosinophil counting criteria but in blood eosinophil count eosinophilia have been observed in below 39%. 8) 75% of the cases showed positive response to allergic skin test. Common positive allergens were House dust(75%), D. farinae(49%), Candida(31%) and so on. 9) The provocative rate to positive skin allergen was 72% for House dust, 40% for D. farinae, 30% for Alternaria and 20% for Aspergillus and so on. 10) The allergens used for hyposensitization were House dust in 61%, D. farinae in 13% and Alternaria in 11% and so on. 11) The erythema and wheal after hyposensitization gradually decreased in width over time. 12) The eosinophil in nasal discharge after hyposensitization gradually decreased over time. 13) The provocative reaction after sensitization was markedly reduced over time. 14) The symptoms gradually disappeared as hyposensitization progressed but only one person did not show improvement among 52 hyposensitizing persons.