Chronic lymphocytic leukemia (CLL) is frequently complicated during its course by autoimmune disorders (from 2 to 12% of cases), such as autoimmune hemolytic anemia (AIHA) and immune thrombocytopenic purpura (ITP). In particular, ITP has been reported in about 2–5% of CLL population. Recently, Cuker et al. reported the occurrence of ITP in 6/216 patients with relapsing-remitting multiple sclerosis in a phase 2 clinical trial of annual alemtuzumab. Alemtuzumab is an anti-CD52 monoclonal antibody used in CLL both as first-line treatment and in relapsed/refractory patients. We evaluated a cohort of 64 consecutive patients affected by relapsed-refractory CLL treated with low-dose alemtuzumab and we observed a incidence of ITP higher than predicted. Our data, associated with the report of Cuker et al., seem to suggest an important role of alemtuzumab in the pathogenesis of ITP which could be related to its induced dysregulation of T-lymphocyte activity.