Inclusion Criteria:

- Patients must have histologically confirmed DLBCL with characteristic
immunophenotypic profiles. Tumor tissue must be confirmed to express the CD20 antigen
by flow cytometry or immunohistochemistry.

- Patients must have at least one site of measurable disease, 1.5 cm in diameter or
greater.

- Patient has not had any previous treatment.

- Stage II (not appropriate for abbreviated chemoimmunotherapy and radiotherapy), III
or IV disease

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

- Patients must have laboratory test results within these ranges:

- Absolute neutrophil count > = 1500/mm³

- Platelet count > = 75,000/mm³

- Serum creatinine < = 1.5X upper limit of normal (ULN)

- Total bilirubin < = 1.5X ULN. Higher levels are acceptable if these can be
attributed to active hemolysis or ineffective erythropoiesis.

- AST (SGOT) and ALT (SGPT) < = 2 x ULN

- Disease free of prior malignancies for > = 5 years with exception of currently
treated basal cell, squamous cell carcinoma of the skin, or carcinoma "in situ" of
the cervix or breast.

- Women of childbearing potential must have a negative serum pregnancy test prior to
azacitidine treatment.

- Women of childbearing potential should be advised to avoid becoming pregnant and men
should be advised to not father a child while receiving treatment with azacitidine.
The effects of azacytidine on the developing human fetus at the recommended
therapeutic dose are unknown. For this reason, women of child-bearing potential and
men must agree to use adequate contraception (hormonal or barrier method of birth
control; abstinence) prior to study entry and for the duration of study
participation. Should a woman become pregnant or suspect she is pregnant while
participating in this study, she should inform her treating physician immediately.

- Age >18 years.

- Ability to understand and the willingness to sign a written informed consent
document.

- ECOG performance status of 0-2

Exclusion Criteria:

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

- Patients 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.

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

- Concurrent use of other anti-cancer agents or treatments.

- Known positive for HIV or infectious hepatitis B.

- Known central nervous system involvement by lymphoma.

- Known or suspected hypersensitivity to azacitidine or mannitol.

- Patients must not have advanced malignant hepatic tumors.

- Pregnant and lactating women are excluded from the study because the risks to an
unborn fetus or potential risks in nursing infants are unknown.