The relevance of the irritant skin reaction of individuals with an atopic history (atopic dermatitis, rhinoconjunctivitis or atopic asthma) to sodium lauryl sulfate (SLS), a widely used irritant, is still controversial. The aim of this study was to evaluate transepidermal water loss (TEWL) as an indicator of stratum corneum integrity, before and after SLS patch testing, in various groups of atopic individuals with and without atopic dermatitits. 95 volunteers were divided into 4 groups: (1) individuals with active atopic dermatitis; (2) individuals with a history of atopic dermatitis but without active skin lesions; (3) individuals with rhinoconjunctivitis or atopic asthma without any symptoms at the time of testing; (4) healthy individuals serving as controls. The volunteers were patch-tested at the unaffected volar side of the forearm with aqueous SLS 0.5% for 48 h. TEWL was measured before application and after removal of the patch. Individuals with active atopic dermatitis showed a significantly higher TEWL value after SLS and a tendency to a higher basal TEWL as compared to the 3 other groups. There were no significant differences in TEWL between individuals who were classified as atopic but without active dermatitis, individuals with rhinoconjunctivitis or atopic asthma and healthy controls, either at the basal or at the post-SLS measurement. Enhanced skin susceptibility is only present in individuals with active dermatitis. The skin susceptibility of atopic individuals might therefore be increased as soon as the skin becomes eczematous, suggesting a reduced epidermal integrity probably caused by the endogenous atopy and/or respiratory allergens. When interpreting the atopy score in relation to skin susceptibility, the actual condition of the skin should hence be taken into consideration.