Immunosuppression with antithymocyte globulin (ATG) or cyclosporine (CSA) can be used to treat the cytopenia associated with myelodysplastic syndrome (MDS). Previously, we identified HLA-DR15, younger age, and shorter duration of red cell transfusion dependence as pretreatment variables that correlate significantly with a response. Using these pretreatment variables we have devised a simple method to prospectively identify patients with low or high probabilities of response to immunosuppression. The ability of this system to predict response was confirmed in a separate cohort of 23 patients with MDS treated with immunosuppression.