Low-dose alemtuzumab has shown a favourable toxicity profile coupled with good results in terms of efficacy in relapsed/refractory chronic lymphocytic leukaemia (CLL). We conducted a multicentre retrospective study on the routine clinical use of low-dose alemtuzumab in this patient setting. One hundred and eight relapsed/refractory CLL patients from 11 Italian centres were included in the analysis. All patients had an Eastern Cooperative Oncology Group performance status ≤2 and the majority (84%) had adenopathies <5 cm. Low-dose alemtuzumab was defined as a total weekly dose ≤45 mg and a cumulative dose ≤600 mg given for up to 18 weeks. The overall response rate was 56% (22% complete remissions). After a median follow-up of 42.2 months, the median overall survival and progression-free survival were 39.0 and 19.4 months, respectively. In univariate analysis, response was inversely associated with lymph node (P = 0.01) and spleen (P = 0.02) size, fludarabine-refractoriness (P = 0.01) and del(11q) (P = 0.009). Advanced age and del(17p) were not associated with a worse outcome. Cumulative dose of alemtuzumab was not associated to response. Toxicities were usually mild and manageable; severe infections occurred in seven patients (7%) during therapy. This retrospective analysis confirms that low-dose alemtuzumab is a valid and currently used therapeutic option for the treatment of relapsed/refractory CLL.