CC chemokine receptor (CCR)4 is selectively expressed on Th2-type T cells and has been shown to be responsible for Th2-dominant immune responses. In this study, we analyzed the expression of CCR4 in active systemic lupus erythematosus (SLE) patients by FACS analysis using anti-human CCR4 monoclonal antibody and determined the clinical relevance in this disease. Higher expression of CCR4 was found on peripheral blood CD4+ T lymphocytes of active SLE patients than was found with healthy controls and inactive SLE patients. The CCR4 expression significantly correlated with the SLE disease activity index (SLEDAI) scores. The expression was dramatically decreased after the corticosteroid therapy in parallel with a serum level of double-stranded DNA antibody and SLEDAI scores. Moreover, we found that serum levels of IL-10 were increased in active SLE patients and significantly correlated with the CCR4 expression. This study suggests that Th2 immune response is predominant in the active state of SLE, and CCR4 may have relevance in regard to the disease course in SLE patients.