|Inclusion Criteria:||1) Understand and voluntarily sign an informed consent form.|
2) Age >/= 18 years at the time of signing the informed consent form.
3) Relapsed/refractory MMM with measurable levels of myeloma paraprotein in serum ( >/= 0.5 g/dl), urine ( >/= 0.2 g excreted in a 24-hour collection sample), or abnormal free light chain (FLC) ratio.
4) Serum Creatnine </= 2.5 mg/dl
5) Eastern Cooperative Oncology Group (ECOG) performance status score of 0, 1, or 2
6) Females of childbearing potential (FCBP)* must have a negative serum or urine pregnancy test with a sensitivity of at least 50 mlU/mL within 10-14 days prior to and again within 24 hours of starting lenalidomide and must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control, one highly effective method and one additional affective method AT THE SAME TIME, at least 28 days before she starts taking lenalidomide.
7) Continuation from Inclusion # 6: FCBP must also agree to ongoing pregnancy testing. Men must agree to use a latex condom during sexual contact with a female of childbearing potential even if they have had a successful vasectomy. All patients must be counseled at a minimum of every 28 days about pregnancy precautions and risks of fetal exposure.
8) Continuation from Inclusion # 7: * A female of childbearing potential is a sexually mature woman who: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months).
9) Laboratory test results within these ranges: Absolute neutrophil count > 1000 cells/mm^3 Platelet count > 50,000 cells/mm^3 for patients with < 50% of bone marrow plasma cells and platelet count > 25,000 cells/mm^3 for patients in whom > 50% of the bone marrow nucleated cells were plasma cells Total bilirubin </= 2.0 mg/dL AST (SGOT) and ALT (AGPT) < 3 x ULN
10) Able to take prophylactic anticoagulation, warfarin or equivalent agent
11) Patient is able to understand and comply with the terms and conditions of the Lenalidomide and Thalidomide Counseling Program
12) All study participants must be registered into the mandatory RevAssist® program, and be willing and able to comply with the requirements of RevAssist®, AND the S.T.E.P.S.® program.