OBJECTIVES: I. Determine whether the addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) increases the failure-free survival of patients with newly diagnosed, previously untreated, aggressive B-cell non-Hodgkin's lymphoma. II. Determine whether the addition of rituximab changes the toxicity profile attributed to CHOP chemotherapy in this patient population.