Objectives-To document and evaluate the outcome of side to side comparisons of diVerent corticosteroids in determining the most eVective topical treatment for individuals admitted to hospital for control of atopic dermatitis. Methods-Retrospective case note study of 82 admissions (66 children) to a children's hospital for treatment of atopic dermatitis between 1 June 1993 and 31 October 1995. DiVerent topical corticosteroid ointments were applied to the two sides of the body. The outcome measure was a comparison between the two sides, to see whether one treatment was better than the other. Results-More potent topical corticosteroid preparations appeared more eVective than weaker preparations on 25 occasions, there was no diVerence on 20 occasions, and on seven occasions a weaker preparation appeared more eVective. Incorporation of an antimicrobial agent did not appear to increase the eYcacy of a preparation. Conclusions-The management of atopic dermatitis is bedevilled by considerable spontaneous fluctuations in severity, leading to uncertainty as to whether a new treatment is beneficial; a coincidental flare up of the skin lesions may be wrongly attributed to a particular treatment, which is then discarded. Comparing different topical treatments simultaneously on opposite sides of the body is a feasible and rational way to determine the optimum treatment for an individual with atopic dermatitis.