Inclusion Criteria:

- Adult patients, >/= 18 years of age

- Previously untreated CD20-positive diffuse large B-cell lymphoma (DLBCL)

- At least 1 bi-dimensionally measurable lesion (>1.5 cm in is largest dimension on the
CT scan)

- Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2

- Adequate hematological function

- Low-intermediate, intermediate or high-risk IPI score (low-risk IPI score: IPI 1
irrespective of bulky disease or IPI 0 with bulky disease, defined as one lesion >/=
7.5 cm)

Exclusion Criteria:

- History of severe allergic or anaphylactic reactions to humanized or murine
monoclonal antibodies or known sensitivity or allergy to murine products

- Contraindication to any of the individual components of CHOP, including prior receipt
of anthracyclines

- Patients with transformed lymphoma and patients with follicular lymphoma IIIB

- Prior therapy for DLBCL, with the exception of nodal biopsy or local irradiation

- Prior treatment with cytotoxic drugs or rituximab for another condition (e.g.,
rheumatoid arthritis) or prior use of an anti-CD20 antibody

- Prior use of any monoclonal antibody within 3 months of the start of Cycle 1

- Ongoing corticosteroid use of > 30 mg/day of prednisone or equivalent

- Primary CNS lymphoma, blastic variant of mantle-cell lymphoma, or histologic evidence
of transformation to a Burkitt lymphoma, primary mediastinal DLBCL, primary effusion
lymphoma, and primary cutaneous DLBCL

- Positive for HIV

- Active hepatitis B or C infection