In patients with low and intermediate-1 risk MDS with an isolated deletion 5q cytogenetic abnormality, red blood cell (RBC) transfusion-dependence is a prevalent condition. For these latter patients reaching transfusion-dependence, lenalidomide, an immunomodulatory drug, has been approved by FDA and EMA. It has been shown that the drug induces significant erythroid (about 65%) and cytogenetic responses which have been associated with a survival benefit. In patients with MDS with del5q and serum erythropoietin levels > 500 miU/L, lenalidomide dosing of 10 mg/day for 21 days every 28, rather than 5 mg dosing, induces higher rates of transfusion-independence and cytogenetic responses with a trend to survival advantage. As a consequence, the recommended starting dose of lenalidomide is 10 mg orally once daily on days 1-21 of repeated 28-day cycles. Lenalidomide treatment must not be started if the Absolute Neutrophil Counts (ANC) < 0.5 Gi/L and/or PLT counts < 25 Gi/L.