Cyclosporin has previously been demonstrated to be effective and well tolerated by children with severe atopic dermatitis (AD) used for a period of six weeks. Preliminary data are now available from a prospective study to determine whether this treatment can be used for a longer period and assess the optimal regimen.Children with severe AD were recruited and randomised into two groups. Both were treated with cyclosporin (Neoral ), 5 mg/kg/day for 8 weeks. In one group the treatment was then tailed off over 4 weeks. In the other the dose was adjusted according to response. Signs were monitored using the SASSAD score, and symptoms using visual analogue scales. Serum creatinine and blood pressure were monitored.Sixteen children were enrolled, aged 5-15. The mean baseline SASSAD score was 43. This fell to 21 by week 8. The mean pruritus score fell from 66 at baseline to 25 at week 8. In 8 subjects for whom treatment was continued the response was maintained while the mean dose was tapered down to 3 mg/kg/day by 16 weeks. In 8 subjects we attempted to tail off the cyclosporin over 4 weeks. This was successful in 5. In one case treatment was recommenced after one week and in two others the eczema deteriorated rapidly as the dose was reduced and it was not possible to discontinue treatment. There were no changes in mean blood pressure or serum creatinine in either group.Cyclosporin appears effective and safe in children with severe (AD) used for up to 16 weeks. Stopping treatment can be difficult due to rapid relapse.