Our previously reported data and similar studies from other institutions indicate that patients with PET positive lesions after salvage chemotherapy and prior ASCT do very poorly. In our study, patients with residual PET positive lesions before ASCT had median PFS of 5 months with only 7% of patients without progression at 12 months after ASCT. It can be speculated that patients with PET positive lesions prior ASCT harbor chemotherapy resistant lymphoma cells in their tumors. Since the mechanism of action of lenalidomide differs from traditional cytotoxic chemotherapy, the use of this novel agent in this group of patients is an attractive concept. The immunomodulary properties of lenalidomide over the maintenance period of 24 months could improve the overall outcome of patients following ASCT. Since there is a valid concern that lenalidomide could cause severe cytopenias when used early after ASCT, we proposed to administer dose 10 mg of lenalidomide daily with an option of dose modification to 5 mg daily according to previously defined toxicity criteria. The daily maintenance dosing of lenalidomide at 10 mg has been used in patients with multiple myeloma after ASCT and improved PFS in two large randomized trials.