Pimecrolimus cream 1% is a topical calcineurin inhibitor for the treatment of atopic dermatitis. Minimal systemic exposure to pimecrolimus has been previously observed in Caucasian pediatric patients treated with the cream twice daily for up to 1 year. The objective of this open-label, non-comparative, multicenter study was to assess the systemic exposure, tolerability and efficacy of pimecrolimus cream 1% when used twice daily for 3 weeks in pediatric patients of Japanese background. The patient cohort consisted of 17 Japanese infants and children (age range, 3.6 months to 11.6 years) with atopic dermatitis of at least mild severity affecting >or=10% of the total body surface area (range, 10-48%). Pimecrolimus cream 1% was applied twice daily for 3 weeks. Blood levels of pimecrolimus were determined on days 1, 10 and 22. Safety and tolerability were evaluated by monitoring adverse events, laboratory parameters, physical condition and vital signs. Efficacy parameters included the Eczema Area and Severity Index, the Investigators' Global Assessment and the pruritus score. The median exposure to pimecrolimus cream 1% was 22 treatment days (range, 9-29 treatment days). Pimecrolimus blood concentrations were <0.5 ng/mL in 94% of samples on day 1, in 93% of samples on day 10 and in 100% of samples on day 22, with no indication of an increase with increasing body surface area treated (up to 48% of the total body surface area). No drug-related systemic adverse events or serious adverse events were reported. Treatment was effective according to all efficacy parameters. The findings of this study indicate that the use of pimecrolimus cream 1% results in minimal systemic absorption of the active ingredient in pediatric patients of Japanese background with extensive disease.