Background: The water content of the stratum corneum and skin surface lipids are important factors in the appearance and function of the skin. A disruption of the balance between the two may lead to the clinical manifestation of dryness of skin in patients with atopic dermatitis. Objective: The aim of our study was to examine the so-called dry skin of patients with atopic dermatitis using objective parameters. We compared the epidermal hydration and the skin surface lipids, the so-called hydro-lipid film, of the clinically unaffected skin of patients suffering from atopic dermatitis with that of healthy subjects. Methods: A total of 48 patients of either gender were included in this retrospective case-control study. We used the Corneometer CM 820 (Courage+Khazaka Electronic GmbH, Cologne, Germany) and the Sebumeter SM 810 (Courage+Khazaka Electronic GmbH) as noninvasive measuring methods. Results: The results showed marked decreases in the atopic dermatitis group for both the Corneometer and Sebumeter measuring methods. Conclusion: Our results show that the dry skin of patients with atopic dermatitis, as previously shown, is due not only to a decrease in skin moisture but also to a reduction of skin lipids. This finding gives rise to a new understanding of the condition, and therefore one should always speak of a hydro-lipid film. (J Am Acad Dermatol 2003;48:352-8.)