OUTLINE: This is a randomized, multicenter study. Patients are stratified according to lymphoma subtype. Patients are randomized to one of two treatment arms. Arm I: Patients receive no further therapy following high dose chemotherapy and autologous stem cell transplantation. Arm II: Beginning 4 weeks after high dose chemotherapy and autologous stem cell transplantation, patients receive interferon alfa-2b subcutaneously three times a week. Treatment continues for 18 months in the absence of disease progression or unacceptable toxicity. Patients are followed every 6 months until disease progression.