DISEASE CHARACTERISTICS: Histologically proven aggressive B-cell non-Hodgkin's lymphoma that has failed prior combination chemotherapy with an anthracycline-containing regimen Eligible histologies: Diffuse large cell Small non-cleaved cell/Burkitt's lymphoma No lymphoblastic or mantle cell lymphoma First relapse or primary refractory disease Ineligible for or refused treatment with salvage chemotherapy followed by high-dose therapy and autologous stem cell rescue Documented CD20 antigen expression Measurable disease No clinical evidence of CNS involvement by lymphoma