Background: Although many recent reports have suggested an important role of cockroach in atopic dermatitis, little is known about the relationship between cockroach hypersensitivity and environmental factors. Object: The purpose of this study was to investigate the associations with cockroach hypersensitivity and environmental factors in patients with atopic dermatitis. Methods : We performed a prick test on 100 patients with atopic dermatitis, allergic rhinitis, asthma and 30 controls with cockroach crude extract(German cockroach, American cockroach, body, egg, feces). Detailed history about various environmental factors were taken. Results : There were significant increases in the positive prick test results in atopic dermatitis, allergic rhinitis, and asthma groups compared with the control group. The positive prick test results were variable according to each environmental factor(residence type, family income, experience in looking cockroach, and exertion for extermination). Conclusion . The higher positive prick test results of atopic dermatitis, allergic rhinitis, and asthma in this study suggest a role of immediate allergic reactions to cockroach antigen. Different prick test results according to each environment could imply that environmental factors have important effects on the development of cockroach hypersensitivity. Positive prick test results with cockroach crude extract were specially high in the group that does not live in the apartment.