Define maximum tolerable dose of the combination lenalidomide, bendamustine, prednisone.

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. Life expectancy of at least 3 months
4. Able to adhere to the study visit schedule and other protocol requirements
5. Relapsed or refractory MM (only first or second relapse) in stage II or III after autologous SCT or conventional chemotherapy (histologically or cytologically proven/ Salmon and Durie criteria) with detectable myeloma protein in blood or urine
6. All previous cancer therapies, including radiation, cytostatic therapy and surgery, must have been discontinued at least 4 weeks prior to treatment in this study, without corticosteroids therapy.
7. ECOG performance status of £ 2 at study entry (see Appendix 01).
8. Laboratory test results within ranges
9. Females of childbearing potential must agree to contraception or abstinence
10. Disease free of prior malignancies for ³ 5 years with exception of currently treated basal cell, squamous cell carcinoma of the skin, or carcinoma "insitu" of the cervix or breast

Exclusion Criteria:

1. Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form.
2. Pregnant or breast feeding females.
3. Any condition, including the presence of laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study or confounds the ability to interpret data from the study.
4. Patients with contraindications (exclusion criteria) for treatment with lenalidomide, bendamustine and prednisone.
5. Uncontrolled or severe cardiovascular disease, including myocardial infarction within 6 months before study entry, New York Heart Association Class III or IV heart failure, uncontrolled angina or severe uncontrolled ventricular arrhythmias (≥ Lown 3).
6. Use of any other experimental drug or therapy within 28 days of baseline.
7. Known hypersensitivity to thalidomide or purine analogues
8. The development of erythema nodosum if characterized by a desquamating rash while taking thalidomide or similar drugs.
9. Any prior use of lenalidomide or bendamustine in the last six months
10. Concurrent use of other anti-cancer agents or treatments other stated in this treatment plan.
11. Known positive for HIV or infectious hepatitis, type A, B or C.