Allo-SCT can result in long-term remission in patients with multiple myeloma (MM), although its overall role in disease management remains controversial. We evaluated lenalidomide monotherapy response and tolerability among 18 patients with MM who progressed or relapsed after Allo-SCT, who were enrolled a median of 12 months (range 3-104) following transplant. Treatment duration of lenalidomide was 8 months (range 1-57). Ten patients required dose reductions from 25 to 5-20 mg at a median of three cycles (range 1-12): eight for neutropenia, one for thrombocytopenia and one for myalgias and weakness. Serious adverse events (N=5) included H1N1 influenza (2), bacterial pneumonia (2) and fever, myalgia and hypoxia. Two patients died at 3 and 5 months of gastrointestinal or hepatic GVHD occurring within 1 month of dosing. Responses included complete response (CR) (5), very good partial response (2), partial response (PR) (3), minimal response (1) and stable disease (2) for an overall response rate (≥ PR) of 56%. Ten patients discontinued therapy for progressive disease (PD) at a median of 8.5 (1-43) months. Six patients died from PD. Five patients remained on therapy at 39 months (range 14-57), with four in CR. Lenalidomide for relapse of MM after Allo-SCT can result in extended disease control (>12 months) in 50% of patients.