OBJECTIVES: I. Determine the rate of complete response and partial response in patients with intermediate or high grade non-Hodgkin's lymphoma treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). II. Determine the toxicity of this regimen in these patients. III. Determine the disease-free and overall survival, time to response, and time to disease progression in patients treated with this regimen.