Inclusion Criteria:

- Understand and voluntarily sign an informed consent form

- Age greater than or equal to 18 and less than or equal to 65 years

- Able to adhere to the study visit schedule and other protocol requirements.

- High risk acute myelogenous leukemia or high risk myelodysplastic syndrome
status post allogeneic bone marrow transplant

- ECOG performance status of less than or equal to 2

- Disease free of other malignancies beside the AML or MDS for ≥ 2 years with exception
of currently treated basal cell, squamous cell carcinoma of the skin, or carcinoma
"in situ" of the cervix or breast.

- All study participants must be registered into the mandatory RevAssist® program, and
be willing and able to comply with the requirements of RevAssist®.

- Females of childbearing potential (FCBP) must have a negative serum or urine
pregnancy test with a sensitivity of at least 50 mIU/mL within 10 - 14 days and again
within 24 hours prior to prescribing lenalidomide for Cycle 1 (prescriptions must be
filled within 7 days as required by RevAssist) 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 effective method AT THE SAME
TIME, at least 28 days before she starts taking lenalidomide. FCBP must also agree
to ongoing pregnancy testing. Men must agree to use a latex condom during sexual
contact with a FCBP even if they have had a successful vasectomy.

- Between 6 months to 8 months post transplant

- Laboratory tests:

- Neutrophil count of ≥ 1.5 x 109/L

- Platelet count ≥ 50 x 109/L

- Calculated creatinine clearance ≥ 60ml/min by Cockcroft-Gault formula

- Total bilirubin ≤1.5 x upper limit of normal

- AST (SGOT) and ALT (SGPT) ≤ 3 x upper limit of normal

Patients are eligible to start on this protocol if they are between 6 months to 10 months
post transplant.

Exclusion Criteria:

- Any serious medical condition, laboratory abnormality, or psychiatric illness that
would prevent the subject from signing the informed consent form

- Pregnant or breast feeding females (Lactating females must agree not to breast feed
while taking lenalidomide)

- Any level of acute graft versus host disease

- Active, uncontrolled infection are not eligible for this study

- 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

- Use of any other experimental drug or therapy within 28 days of baseline.

- Known hypersensitivity to thalidomide

- Development of erythema nodosum if characterized by a desquamating rash while taking
thalidomide or similar drug

- Known sero-positive for active viral infection with HI, hepatitis B virus (HBV) or
hepatitis C virus (HCV)

- Mixed chimerism (at 6 months post transplant will not be started on the protocol

- Active AML or MDS at the time of the study are not eligible for this protocol

- Not able to swallow the lenalidomide capsule as a whole are excluded from this study

- Impaired gastrointestinal absorption