Lenalidomide is a novel thalidomide analogue with enhanced immunomodulatory and antiangiogenic action lacking most of the typical thalidomide-associated adverse events. In myelodysplastic syndromes (MDS), it has been used primarily in the IPSS low- and intermediate-1 risk setting. Several trials have demonstrated its potential to lead to both erythroid and cytogenetic responses in these disease groups. In a clinical trial of patients with a del(5q) chromosomal abnormality, lenalidomide treatment resulted in red blood cell (RBC) transfusion independence in 67% of patients. Moreover, 45% of patients achieved a complete cytogenetic remission, and 28% achieved a minor cytogenetic remission. This result was independent of karyotype complexity. Lenalidomide might also induce long-term remissions in del(5q) patients with an elevated medullary blast count. In non-del(5q) patients, 43% of patients with confirmed low- and intermediate-1 risk achieved transfusion independence or a reduction of at least 50% of pre-treatment RBC transfusion levels. Adverse events are common but manageable and include neutropenia and thrombocytopenia, pruritus, rash, diarrhea, and others. Lenalidomide will prove an essential part in the armamentarium of MDS therapeutics. Combination therapies with cytokines, demethylating agents, tyrosine kinase inhibitors, or chemotherapy are being investigated and may show additional benefit in both low- and high risk MDS.