The outlook for individual patients with chronic lymphocytic leukaemia (CLL) has always been difficult to predict. This situation has led to the development of a plethora of prognostic markers, but nearly all studies have shown that 17p deletion consistently confers the worst outcome of all subtypes of CLL, with typical survival of 2–3 years as a result of low proportions of patients responding to primary chemo-immunotherapy and short progression-free survival. This cytogenetic lesion is quite rare in newly diagnosed patients (occurring in in 5–10% of such cases) but is much more prevalent in the relapsed and refractory setting (in up to 50% of patients).1