Chronic lymphocytic leukaemia (CLL) patients in early clinical stage (Binet A; Rai 0) with nondiffuse bone marrow histopathology and low stable blood lymphocyte levels have long survival rates and should not be treated unless the disease progresses. In contrast, patients with poor prognostic features, such as advanced clinical stage (Binet B, C; Rai III, IV), diffuse bone marrow infiltration or high and rapidly increasing blood lymphocyte levels, have a median survival of less than 5 years and need therapy. Chlorambucil is still the mainstay for CLL treatment. Compared with chlorambucil, combination chemotherapy produces higher remission rates but no increases in survival. New agents such as fludarabine and 2-chlorodeoxyadenosine are already the treatment of choice for patients failing standard therapies, and their role as front-line therapy is being investigated in randomised trials. Whatever the treatment used, however, cure is rarely achieved. Certain situations (e.g. autoimmune cytopenias, hypersplenism) require special treatment approaches (e.g. corticosteroids, splenectomy). Bone marrow transplants, albeit experimental in CLL, warrant investigation in younger patients with poor prognosis.