SummaryBackground Atopic dermatitis (AD) is a chronic allergic inflammatory disease, which manifests itself with eczematous skin lesions. Objective We compared the clinical efficacy of tacrolimus ointment (0.1%) given twice a day and oral cyclosporine (3 mg/kg) given once daily. Rescue medication for itching included cetirizine 10-20 mg (equal to one or two tables). Methods Thirty patients, aged 13-45 years (mean AE SD 27.1 AE 10.9), with a history of moderateto-severe AD were randomized to treatments, 15 patients for each treatments. Assessment of efficacy was based on SCORAD, on scores of daily itching, erythema, interference with sleep, due to the skin condition and days without use of cetirizine tablets. SCORAD, measured on a scale (0-103), was evaluated before treatment (0) and at 7, 14, 21, 28, 35 and 42 days after treatment. Similarly, the means of daily symptoms, on a scale (0-3), were evaluated before the treatment (0) and at 7, 14, 21, 28, 35 and 42 days after treatment; finally, on day without use of cetirizine tablets. The safety of the study treatments was assessed through haematologic, biochemical and urinary testing and on systolic and diastolic blood pressures and heart rate measurements. Results SCORAD decreased in the two treatment groups 14 days after the beginning of the period study. However, the patients in tacrolimus ointment group reported significantly lower SCORAD than those treated with oral cyclosporine. Overall SCORAD, as assessed by the area under the curve (AUC) day 0-42 (score/day), was significantly lower in the tacrolimus ointment group when compared with oral cyclosporine (Po0.001). Similarly, AUC day 0-42 (score/day) for itching, erythema and number of nights without interference with the sleep due to skin condition were significantly lower in the group of patients treated with tacrolimus compared with those treated with cyclosporine (P 5 0.003, 0.005 and 0.01, respectively). As regards the use of rescue medication, expressed by median of number of days without use of anti-H 1 , it was significantly lower in the group treated with tacrolimus (82.5) than in the cyclosporine group (76.5) (P 5 0.03). There were no appreciable changes in haematological and biochemical indices, in both treatments groups. Conclusion The results of this comparative study demonstrate that tacrolimus ointment twice daily and cyclosporine administered orally once daily are effective on SCORAD, daily symptoms and anti-H 1 rescue. When we compared tacrolimus and cyclosporine there was a faster onset of action in the group treated with tacrolimus. The two drugs presented the same safety. However, these data support the preferential use of topical tacrolimus 0.1% in AD, because cyclosporine has potential side-effects.