PURPOSE To investigate the changes of effector-related phenotypic markers and the natural killer (NK)-like effector functions of CD8(bright)CD56+ T cells in patients with Behçet uveitis after combined cyclosporine and prednisone (Cs/Pd) treatment. METHODS Ten patients with active Behçet panuveitis and 10 healthy controls were prospectively recruited in this study. The effector-related surface markers (CD27, CD62L, CD11b, HLA-DR, CD94, NKG2D), chemokine receptors (CXCR1, CXCR3, CCR4, CCR5), and intracellular perforin of circulating CD8(bright)CD56+ T cells were determined by flow cytometric analysis before and after two months' treatment. NK-like cytotoxicity of ex vivo CD8(bright)CD56+ T cells against K562 was measured by standard 51Cr release assay. RESULTS The expression levels of effector-related molecules on CD8(bright)CD56+ T cells normalized after treatment. The expression levels of CXCR1 and CCR5 were down-regulated on CD8(bright)CD56+ T cells after treatment. The amounts of preformed intracellular perforin of CD8(bright)CD56+ T cells were reduced to the normal levels. Furthermore, the NK-like cytolytic capacities of CD8(bright)CD56+ T cells were decreased after treatment. CONCLUSIONS Our results suggest that the combined Cs/Pd treatments in active Behçet uveitis may downregulate the NK-like effector functions of CD8(bright)CD56+ T cells.