OUTLINE: This is a randomized, open-label, multicenter study. Patients are stratified according to age (60 and over vs under 60). Within 60-100 days after autologous stem cell transplantation, patients are randomized to 1 of 2 treatment arms. Arm I: Patients receive lower dose oral thalidomide daily and oral prednisone every other day. Arm II: Patients receive higher dose thalidomide daily and oral prednisone every other day. Treatment continues for 2 years in the absence of disease progression or unacceptable toxicity. Patients are followed monthly for 6 months, every 3 months, and then at time of disease progression.