Background: Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease with genetic and environmental background. The diagnosis of AD depends on the clinical presentation and history because there are no objective laboratory tests. The criteria established by Hanifin and Rajka have become the standard for the clinical diagnosis of AD (Until now, we used conventional Hanifin and Rajka`s diagnostic guidelines). But diagnostic criteria for Korean have not been studied yet. Objective: The purpose of the present study was to establish the diagnostic criteria of Korean AD. Methods: We made out a draft for diagnostic criteria for Korean on the basis of the Hanifin and Rajka`s guidelines and published Korean journals. And we established the diagnostic criteria for Korean after collecting extensive opinions from dermatologic specialists in many university hospitals. Results: The major criteria of AD is similar to conventional diagnosic criteria, but three additional minor features(periauricular eczema, scalp scale, skin prick test reactivity) were significant for the diagnosis of AD in Korean patients. The other eleven minor features of the conventional minor diagnostic features were also significant. Conclusion: We established Korean diagnostic criteria for AD. Our result suggest that ethnic backgrounds influence the phenotype of AD and that additional three features need to be included in the Korean diagnostic criteria. Continued refinement of these guidelines will facilitate diagnosis in specific ethnic populations and in specific subgroups of patients. (Korean J Dermatol 2006;44(6):659~663)