Inclusion Criteria:

          -  Patients eligible include those with diagnosis of AML other than acute promyelocytic
             leukemia by World Health Organization (WHO) criteria with relapsed disease after
             induction therapy or refractory to induction chemotherapy, as determined by morphology
             on bone marrow biopsy; also eligible are patients unwilling to receive standard
             induction chemotherapy

          -  Eastern Cooperative Oncology Group (ECOG) performance status 0-2

          -  Serum creatinine =< 1.5 mg/dL; if serum creatinine > 1.5 mg/dL, then the estimated
             glomerular filtrate rate (GFR) must be > 60ml/min/1.73m^2 as calculated by the
             Modification of Diet in Renal Disease equation

          -  Serum bilirubin =< 1.5 x upper limit of normal (ULN) unless elevation is considered to
             be secondary to Gilbert's syndrome, hemolysis, or hepatic infiltration by AML

          -  Aspartate transaminase (AST)/alanine transaminase (ALT) =< 2.5 x ULN

          -  Alkaline phosphatase =< 2.5 x ULN

          -  All study participants must be registered into the mandatory Revlimid assistance
             (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

        Exclusion Criteria:

          -  Patient must not undergo concomitant radiotherapy, chemotherapy or immunotherapy;
             patient must not be in concurrent study with other investigational agents

          -  Patients who have received prior lenalidomide therapy are not eligible for this study;
             further there should be at least a 14-day window from the patient's last prior therapy
             before initiation of treatment on clinical trial

          -  Have other severe concurrent disease or serious organ dysfunction involving the heart,
             kidney, liver or other organ system that may place the patient at undue risk to
             undergo treatment

          -  Have significant, uncontrolled active infection

          -  Pregnant or nursing patients will be excluded from the study

          -  Known human immunodeficiency virus (HIV) infection