PURPOSE The clinical efficacy of subcutaneous allergen immunotherapy (SCIT) for the treatment of patients with severe atopic dermatitis (AD) using house dust mite (HDM) extract has been reported. Cyclosporin has been regarded as an effective medication for treatment of severe AD. In this study, we investigated a clinical usefulness of combined treatment with SCIT and cyclosporin in patients with severe AD. MATERIALS AND METHODS Nine patients with severe AD and hypersensitivity to HDM were treated with a combination of SCIT using HDM extract and cyclosporin for 12 months. The primary efficacy outcome was the change in the standardized clinical severity scoring system for AD (SCORAD) values, measured at 6 and 12 months, in comparison with the values at baseline. Daily dose of cyclosporin was decreased or discontinued according to the degrees of clinical improvements in individual patients. RESULTS In 8 patients who completed 12 months of treatment, the SCORAD values significantly decreased from 71.5 ± 15.5 (mean ± SD) at baseline to 20.4 ± 14.6 at 6 months and 26.3 ± 13.6 at 12 months (Wilcoxon signed-rank test, p=0.01), and no significant systemic side effects were observed. Cyclosporin was discontinued in 4 of 8 patients within 8 months after starting the combined treatment. CONCLUSION In this study, combined treatment with SCIT and cyclosporin resulted in significant clinical improvements in patients with severe AD. Further studies are needed to test the clinical usefulness of this combined treatment for patients with severe AD.