Rituximab is an anti-CD20 human-mouse chimeric monoclonal antibody indicated for the treatment of relapsed or refractory, low-grade or follicular, CD20-positive, B-cell NHL. The use of rituximab, as monotherapy, results in significant responses and durations of response in patients with indolent non-Hodgkin's lymphoma (NHL); its efficacy improves even further when used in combination with chemotherapy for both indolent and aggressive NHL. Responses to rituximab treatment vary by the histologic subtype of NHL. In patients with low-grade follicular lymphoma, response rates are approximately 70% to 75% with first-line therapy. On the other hand, patients with diffuse B-cell large-cell lymphoma (DBLCL), single-agent rituximab results in response rates of 30% to 40% have been reported. Rituximab significantly increases response rates when used in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone.