BACKGROUND: Topical glucocorticosteroids are the gold standard in treatment of atopic dermatitis (AD). Recently, topical calcineurin inhibitors have been developed for treatment of this condition. This study compared efficacy and safety of 0.1% methylprednisolone aceponate (MPA) ointment with 0.03% tacrolimus ointment for 3 weeks, in children and adolescents with severe to very severe flare of AD. METHODS: The primary end point was treatment success, defined as a score of 'clear' or 'almost clear' in the static Investigator's Global Assessment (IGA) score. Secondary end points were the percentage change in the Eczema Area and Severity Index (EASI) and patients' assessment of itch and sleep, Children's Dermatology Life Quality Index, patient's assessment of global response, affected Body Surface Area and medication costs. RESULTS: 265 patients were randomized to either MPA (n = 129) or tacrolimus (n = 136) treatment, 257 patients completed the study. Methylprednisolone aceponate 0.1% ointment once daily provided rapid and relevant clinical benefit. Tacrolimus 0.03% ointment twice daily was equally effective with regard to success rate. Methylprednisolone aceponate was superior to tacrolimus for EASI, itch and sleep. Both treatments were well tolerated. Drug-related adverse events were only observed in the tacrolimus group. Medication costs were significantly lower for MPA. CONCLUSIONS: While both treatment groups showed similar efficacy results regarding treatment success (IGA), significant advantages were observed for EASI, itch and sleep with MPA 0.1%. These advantages and the significantly lower treatment costs highlight the benefits of MPA treatment, underlining its first-line role in treatment of children and adolescents with severe AD.