OUTLINE: This is a multicenter study. Patients are stratified according to prior chemotherapy (no prior chemotherapy for chronic lymphocytic leukemia vs prior purine analog-based therapy [fludarabine or cladribine] but no alkylator therapy vs prior alkylator-based therapy [chlorambucil or cyclophosphamide] but no prior purine analog therapy vs prior therapy with alkylators and purine analogs, but not as combination therapy).