Lenalidomide (Revlimid(®)), a thalidomide analogue, is an orally administered second generation immunomodulator with anti-angiogenic, antineoplastic, anti-inflammatory and pro-erythropoietic properties. It is approved for the treatment of patients with transfusion-dependent anaemia due to International Prognostic Scoring System low- or intermediate-1-risk myelodysplastic syndrome (MDS) associated with either chromosome 5q deletion [del(5q)] with or without additional cytogenetic abnormalities (US, Japan and Switzerland etc.), or with an isolated del(5q) cytogenetic abnormality when other therapeutic options are insufficient or inadequate (EU) [featured indication]. In a randomized, double-blind, multicentre, registrational trial (MDS-004; n = 205) in this patient population, a significantly higher proportion of lenalidomide recipients than placebo recipients achieved red blood cell transfusion independence for ≥26 consecutive weeks (primary endpoint for efficacy) and cytogenetic responses. The erythroid response to lenalidomide was accompanied by an increase in the haemoglobin levels. These efficacy outcomes are generally consistent with those seen in an earlier noncomparative registrational trial (MDS-003; n = 148). In MDS-004, lenalidomide also significantly improved health-related quality of life compared with placebo at 12 weeks. Retrospective analyses that compared outcomes between lenalidomide-treated patients with low- or intermediate-1-risk del(5q) MDS and multicentre registry cohorts showed that lenalidomide treatment did not appear to increase the risk of progression to acute myeloid leukaemia. Lenalidomide had a manageable safety profile in the registrational trials, with ≤20 % of patients discontinuing treatment because of adverse events. The most common adverse events (incidence ≥20 %) occurring in lenalidomide recipients were thrombocytopenia and neutropenia, which were generally managed by dosage reductions and/or interruptions, and/or pharmacotherapy. Thus, lenalidomide is a useful option for the treatment of patients with transfusion-dependent anaemia due to low- or intermediate-1-risk del(5q) MDS, with or without additional cytogenetic abnormalities.