Myelodysplastic syndrome (MDS) with isolated del (5q) is an MDS characterized by anemia with or without other cytopenias and/or thrombocytosis and in which the cytogenetic abnormality del(5q) occurs either in isolation or with one other abnormality, other than monosomy 7 or del (7q) (1, 2). Lenalidomide, an immunomodulator drug, has been reported to have dramatic therapeutic efficacy in patients with the 5q- syndrome.