Inclusion Criteria:

1. Patient or their authorized legally acceptable representative must consent to be in the study and must have signed and dated an approved consent form which conforms to federal and institutional guidelines.
2. Age ≥ 18 years and without a maximum age.
3. All patients of reproductive potential should not plan on conceiving children during the treatment program and must agree to use a medically accepted form of contraception.
4. Women of childbearing potential must have a negative serum pregnancy test within 2 weeks of beginning treatment.
5. Patients must have relapsed lymphoma.
6. ECOG performance status of 2 or better.

Exclusion Criteria:

1. Pregnant or breast-feeding at the time of proposed study entry
2. Clinical AIDS or ARS or known positive HIV serology
3. History of malignant neoplasm, other than lymphoma, treated within two years prior to study entry (other than non-melanoma skin cancer or in situ cervical cancer) or where there is current evidence of recurrent or metastatic disease
4. Psychiatric or additive disorders that would preclude obtaining informed consent
5. Serum bilirubin > 1.5 times the upper limit of the normal range for the laboratory (ULN). Higher levels are acceptable if these are attributed to active hemolysis
6. Serum glutamic-oxaloacetic transaminase (SGOT) (aspartate aminotransferase [AST]) or serum glutamic-pyruvic transaminase (SGPT) (alanine aminotransferase [ALT]) levels > 2 times ULN
7. Serum creatinine levels > 1.5 times ULN
8. Platelets < 75,000/mm3
9. Absolute neutrophil count < 1500/mm3
10. Active infection including viral hepatitis
11. Known or suspected hypersensitivity to mannitol, azacitidine, or rituximab
12. Grade 3 or 4 neuropathy
13. Advanced hepatic tumors
14. Uncompensated heart failure