OBJECTIVES: The aim of the study was to identify the chemotherapeutic treatment patterns and associated costs in patients with chronic lymphocytic leukemia (CLL) in the Private Healthcare System.  METHODS: A retrospective analysis of the Orizon database, containing inpatient and outpatient claims data of a pool of 102 HMOs (34% of the total Private Health System), from Jan/2009 to Dec/2012 was conducted. Eligibility criteria were patients starting CLL (ICD-10 code C911) chemotherapy treatment from Apr/2009 to Dec/2012. This cohort of patients was followed until Dec/2012, death or loss of follow-up. Chemotherapy regimens were identified based on the agents reported in the claims. Line of treatment was defined based on meaningful interruption (>6 months) and/or change in the chemotherapy regimen. Descriptive statistics (average, standard deviation and percentage) of treatment regimens, duration of treatment and costs were performed.  RESULTS: 163 patients representing 859 cycles of chemotherapy met eligibility criteria.  43.6% of the patients underwent more than one line of treatment, with total chemotherapy costs of R$84,979.63 per patient. The three most widely used chemotherapy regimen were: fludarabine, cyclofosfamide and rituximab (FCR), used in 81 (54.9%) patients with average treatment duration of 3.54 cycles and total costs of R$69,241.91 per patient; rituximab monotherapy, used in 44 (27.0%) patients, with average treatment duration of 4.05 cycles and total costs of R$59,543.12 per patient; and fludarabine and cyclofosfamide (FC), used in 19 (11.7%) patients, with average duration of 2.22 cycles and total costs of R$7,075.95 per patient. Chemotherapy drugs accounted for 72.8% of the total costs, followed by other medicines (11%), disposable devices (5.5%) and hospital facility fees (5.0%).  CONCLUSIONS: FCR is the standard of care in CLL patients treated in the Brazilian Private Health System, and almost half of the patients undergo more than one treatment line, creating a significant financial burden to private payers.