OBJECTIVE: To evaluate whether mycophenolate mofetil, a new immunosuppressive agent, is effective for treating moderate-severe atopic dermatitis (AD). DESIGN: In an open-label pilot study, mycophenolate mofetil, 1 g, was given orally twice daily for 4 weeks. At week 5, the dosage was reduced to 500 mg twice daily until study end (week 8). Patients were followed up for 20 weeks. SETTING: University hospital dermatology department. PATIENTS: Ten consecutive patients with moderate-severe AD nonresponsive to standard therapy. MAIN OUTCOME MEASURE: Severity of AD as measured using the subjective SCORAD [SCORing Atopic Dermatitis] index. RESULTS: Clinical efficacy was measured every 2 weeks using the subjective SCORAD index. Treatment with mycophenolate notably reduced the severity of AD within 4 weeks in all patients (P<.05), and after 8 weeks the mean +/- SD SCORAD index dropped from the pretreatment value of 49.2 +/- 13.8 to 21.9 +/- 26.5 (P<.01). One patient had to discontinue mycophenolate therapy after 4 weeks because of the development of herpes retinitis. Except for this event, mycophenolate was tolerated well in all patients. Six of 7 patients who had responded to mycophenolate monotherapy had no relapse of disease during 20-week follow-up. In the 7 patients who finished the study, the SCORAD index was reduced by 74%, from 44.0 +/- 7.8 before treatment to 11.4 +/- 5.9 at 20-week follow-up. CONCLUSIONS: Mycophenolate is a highly effective drug for treating moderate-severe AD, with no serious adverse effects occurring in any patients. Thus, mycophenolate might develop into a promising alternative in the therapy of moderate-severe AD.