B cell chronic lymphocytic leukaemia (CLL) is the most common leukaemia in the Western world. It is wrongly considered to be an indolent disease: even patients with Binet stage A can have disease-related morbidity, necessitating treatment in about 50% of them, and over 25% of these patients will die of CLL-related causes. It was recently discovered that there are in fact 2 subtypes of CLL: a pre-germinal centre type. Characterised by unmutated genes which code for the variable parts of immunoglobulin chains (IgV), and a post-germinal centre variant, characterised by IgV somatic mutations. This IgV-gene mutational status as well as surface expression of CD38 and characteristic cytogenic abnormalities has recently been shown to be powerful prognostic factors. Furthermore, over the past few years new treatment modalities have been developed including purine analogues, immunotherapy with monoclonal antibodies and stem cell transplantation. Therefore it is time to substitute the present policy used for the vast majority of patients (i.e. an expectant approach, if needs be followed by initial treatment with chlorambucil) with an approach based on the patient's individual risk profile. This should preferably be done within the framework of clinical trials.