DISEASE CHARACTERISTICS: Diagnosis of intermediate grade B-cell CD20+ non-Hodgkin's lymphoma Failed to achieve initial complete response (CR) after at least 2 courses of standard chemotherapy OR Relapsed after CR and not eligible for autologous bone marrow transplant Measurable disease defined as one of the following: Bidimensionally measurable disease at least 2 cm in diameter by radiograph or CT scan Enlarged spleen extending at least 2 cm below the costal due to lymphomatous involvement Enlarged liver with focal lesions on CT scan or biopsy proven lesions Lymphomatous hepatic involvement must be biopsy proven for the liver to be sole area of measurable disease No evidence of CNS involvement A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology.