Atopic dermatitis (AD), one of the most common skin disorders seen in infants and children, usually has its onset during the first 6 months of life. The prevalence of AD is similar in the United States, Europe, and Japan and is increasing, similar to that of other atopic disorders, particularly asthma. AD has been classified into 3 sequential phases: infantile, childhood, and adult, each with characteristic physical findings. AD has a tremendously negative effect on the quality of life of patients as well as family, most commonly disturbing sleep. The condition also creates a great financial burden for both the family and society. The cutaneous manifestations of atopy often represent the beginning of the atopic march. On the basis of several longitudinal studies, approximately half of AD patients will develop asthma, particularly with severe AD, and two thirds will develop allergic rhinitis. Epicutaneous sensitization has been thought to be responsible, with subsequent migration of sensitized T cells into the nose and airways, causing upper and lower airway disease. Animal models and human observation concur with this theory. Preliminary prevention studies with oral antihistamines provide evidence that early intervention might slow the atopic march.