 It will continue until 500 subjects have commenced the third cycle of treatment with lenalidomide. As a condition of market authorization, subjects should be chosen among relapsedrefractory multiple myeloma patients who have received at least one prior antimyeloma chemotherapy regimen excluding treatment regimens with steroid only with adequate dose and duration 2 cycles or who have relapsedrefractory multiple myeloma after stem cell transplantation. Patients who are eligible for the study will be consecutively enrolled in the study until the targeted patient number is reached. The responsible investigator will be requested to keep a log of subjects who are invited to enter the study. In the case of any of these subjects will not be enrolled in the study, this information will be documented together with its reason. 