[en] BACKGROUND: There is ample evidence that the skin barrier function is altered in atopic dermatitis. Little information is available about the effect of topical corticosteroids and calcineurin inhibitors on this function. PURPOSE: To assess the water content and its rate of accumulation in the stratum corneum of atopic patients using an indirect electrometric method while on tacrolimus or betamethasone valerate treatment. METHOD: Twenty-one patients with moderate atopic dermatitis affecting both forearms completed this double-blind randomized study. One forearm was treated twice daily for 3 weeks with 0.1% tacrolimus ointment. The other forearm was similarly treated with 0.12% betamethasone valerate ointment. Electrometric measurements were made under continuous occlusion secured by a Nova Dermal Phase Meter sensor probe. Assessments were performed at inclusion, after the 3-week treatment and after a further 3-week follow-up out of treatment. RESULTS: During treatment, both compounds yielded a similar improvement in skin barrier function. Indeed, under probe occlusion, the rate of water accumulation was significantly decreased. This improvement was sustained after stopping the tacrolimus treatment. By contrast, the benefit was in part lost at the site that had been treated by betamethasone valerate. CONCLUSION: The difference in the effect of the 2 compounds may be due to the negative influence of betamethasone valerate on the epidermal metabolism leading to progressive atrophy of the tissue. The better preservation of the skin barrier function after stopping tacrolimus treatment may help retarding relapses of atopic dermatitis.