OBJECTIVES: To understand real-world treatment patterns of CLL, the use of agents/regimens across all lines of therapy was evaluated in EU5 countries during the years 2010-2013.   METHODS: IPSOS Healthcare projected rituximab use for the treatment of CLL based on patient diaries. Representative panels of oncologists (N = 509) completed forms directly from reviews of patients' charts and provided information on how they manage patients in everyday practice. A total of 104 physicians provided CLL patient information across first-, second-, and third-line CLL treatments. Important data such as age, comorbidities, and therapy goals were also abstracted. RESULTS: According to the most recent annually projected data, a total of 37,119 patients with CLL are estimated to have been treated in the EU5 with any anticancer drug therapy between July 2012 and June 2013. The majority of these patients (23.1%) are estimated to have received fludarabine-cyclophosphamide-rituximab followed by bendamustine-rituximab (17.4%), chlorambucil (16.2%), fludarabine (7.2%), single-agent rituximab (5.8%), and chlorambucil-rituximab (5.6%). The data show higher rituximab monotherapy share in later lines of therapy for CLL (first-line, 0.3%; second-line, 8.2%, third-line or more, 22.1%) irrespective of age. Approved monoclonals (alemtuzumab, 2%, and ofatumumab, 4%) are not widely used in relapsed CLL. Our data also indicates that single-agent rituximab is now more commonly used in clinical practice than chlorambucil (22.1% vs