Dose reductions or interruptions may be required to manage treatment-associated adverse events among patients with myelodysplastic syndromes (MDS) treated with lenalidomide; such modifications are recommended to sustain therapy and maximize treatment duration. The aim of this retrospective case-control study was to determine the relationship between lenalidomide dose modification (DM), duration of lenalidomide therapy (DOT), and patient outcomes in patients with MDS. Those patients with database follow-up >20months (n=305) were more likely to have received erythropoiesis-stimulating agents (ESAs) (P=0.004), had longer median DOT (P<0.001), and higher rate of DM (P<0.001) versus those with shorter follow-up (n=306). Multivariate analysis indicated that lenalidomide DM (odds ratio [OR] 1.08) and prior ESA treatment (OR 2.40) were significantly associated with longer follow-up; transfusion dependence before lenalidomide initiation was associated with a significantly shorter follow-up (OR 0.60). These data suggest that effective management of lenalidomide treatment using dose reduction and/or delay is associated with longer DOT, which can improve patient outcomes.