Inclusion Criteria:

- Patient must be able to understand and voluntarily sign an informed consent form.

- Patient must be ≥ 18 years old.

- Patient must be able to adhere to the study visit schedule and other protocol
requirements.

- Patient must have histologically confirmed Myelodysplastic Syndrome as defined by FAB
Classification including CMML and secondary MDS which has either:

- progressed at any time during treatment with hypomethylating agents

- failed to achieve a response after 6 cycles

- progressed after treatment with hypomethylating agents had been discontinued
Criteria for response and for progression as defined by revised IWG criteria

- Patient must have discontinued all previous cancer therapy, including radiation,
hormonal therapy and surgery at least 4 weeks prior to treatment in this study.

- Patient must have an ECOG performance status of ≤ 2 at study entry

- Patient must have laboratory test results within these ranges:

- calculated creatinine clearance ≥ 30ml/min by Cockcroft-Gault formula

- total bilirubin ≤ 1.5 x ULN

- AST (SGOT) and ALT (SGPT) ≤ 3 x ULN

- Patient must be disease free of prior malignancies for at least 5 years with
exception of currently treated basal cell, squamous cell carcinoma of the skin, or
carcinoma "in situ" of the cervix or breast.

- Patient must be registered into the mandatory RevAssist® program and be willing and
able to comply with the requirements of RevAssist®.

- If a female of childbearing potential (FCBP), patient must have a negative serum or
urine pregnancy test with a sensitivity of at least 50 mIU/mL within 10 to 14 days
prior to initiation of therapy and again within 24 hours prior to prescribing
lenalidomide for Cycle 1 (prescriptions must be filled within 7 days).

A FCBP is defined as 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).

-If a FCBP, patient must agree to use two reliable forms of contraception simultaneously
or to practice complete abstinence from heterosexual intercourse during the following time
periods related to this study: 1) for at least 28 days before starting study drug; 2)
while participating in the study; and 3) for at least 28 days after discontinuation from
the study. The two methods of reliable contraception must include one highly effective
method (i.e. intrauterine device (IUD), hormonal [birth control pills, injections, or
implants], tubal ligation, partner's vasectomy) and one additional effective (barrier)
method (i.e. latex condom, diaphragm, cervical cap). FCBP must be referred to a qualified
provider of contraceptive methods if needed

Exclusion Criteria:

- Patient must not have any serious medical condition, laboratory abnormality, or
psychiatric illness that would prevent the subject from signing the informed consent
form.

- Patient must not be pregnant or breastfeeding.

- Patient must not have 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.

- Patient must not use any other experimental drug or therapy within 28 days of
baseline.

- Patient must not have a known hypersensitivity to thalidomide.

- Patient must not have developed of erythema nodosum if characterized by a
desquamating rash while taking thalidomide or similar drugs.

- Patient must not have any prior use of lenalidomide.

- Patient must not be concurrently using other anti-cancer agents or treatments.

- Patient must not have known seropositivity for or active viral infection with human
immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV).
Patients who are seropositive because of hepatitis B virus vaccine are eligible.