Chronic lymphocytic leukemia (CLL) is the most common of adult leukemias, comprising about 30-40% of all cases (Watson, 2008). Incidence of CLL varies worldwide, being 4.3/100 000 in Caucasian men and increases with age, with median age at diagnosis of 64-70 years (Yamamoto, 2005). In a phase III trial (CLL-8), the combined immunochemotherapy R-FC (rituximab plus fludarabine and cyclophosphamide) showed longer progression-free and overall survival, higher complete response rate and longer duration of response  than FC alone in previously untreated CLL patients. OBJECTIVES: To assess the incremental cost-utility ratio for R-FC versus FC alone in untreated CLL patients under the public payer perspective in Brazil. METHODS: The cost-effectiveness analysis was based on the pivotal study ML17102 (CLL-8).  A Markov model was developed consisting of three health states: “Progression-Free Survival” (PFS), “Progression” and “Death”. The model cycle length is monthly and the time horizon of the analysis is 15 years. Costing was based on public sources. Only direct costs were considered in the calculation, including costs for treating severe adverse events and further treatment patterns. Costs were reported in 2010 (US$1.00~$Brz1.8) Brazilian Reais and discounted at a 5% rate according to local guidelines for economic evaluation (Vianna, 2007). RESULTS: R-FC combined therapy resulted in a gain of 1.031 life years (Lys) (5.611 vs. 4.579) at an incremental cost of $Brz44,780. The ICER of R-FC vs. FC is, therefore, estimated to be $Brz43,414 per LY gained. The probability of R-FC being cost-effective is 98.84%, considering a willingness-to-pay of R$100,000. CONCLUSIONS: In untreated CLL patients, R-FC therapy improves overall survival and progression-free survival compared with FC alone. Results suggest that F-CR combined therapy is a cost-effective intervention for the Brazilian Public Healthcare System.