OBJECTIVES: Colorectal cancer (CRC) is the third most frequent worldwide and about 28,110 new cases were expect for Brazil in 2010. Two biologic agents are approved for treatment of mCRC in Brazil: cetuximab, exclusively for K-RAS wild-type patients and bevacizumab, for both K-RAS types. We aimed to compare costs and outcomes of bevacizumab versus cetuximab in first-line treatment of mCRC, both in combination with FOLFIRI from a private payer perspective in Brazil.    METHODS: In the absence of head-to-head trials comparing Bev+FOLFIRI and Cet+FOLFIRI, an adjusted indirect comparison was conducted using Bucher-method. Hazard ratios (HRs) from 3 studies: BICC-C(part II) comparing Bev+FOLFIRI vs Bev+IFL; AVF2107g comparing Bev+IFL vs IFL; and CRYSTAL comparing Cet+FOLFIR versus FOLFIRI; were utilized. An illness-death Markov model was enhanced. Risks for progression and mortality were derived from Weibull regression model (assuming deaths conditional upon prior progression). Natural mortality rates were applied according to IBGE life table. Only direct costs were considered for patients with 1,78m² and 70Kg. Ex-factory prices were obtained from official public sources. Time-horizon was two years according to natural history of the disease. Utilities were derived from international sources; discounting was 5% for costs and outcomes, according to local guidelines. A probabilistic sensitivity analysis (PSA) was conducted in order to evaluate the robustness of results. Non-statistically significant HR 95%-CIs were exploited in PSA. RESULTS: Results of the analysis suggest Bev+FOLFIRI combination is less costly compared to Cet+FOLFIRI ($Brz216,838.38 vs. $Brz276,770.15) and a trend towards improved effectiveness with Bev+FOLFIRI (OS 20.1 vs. 16.60 months; QALYs 1.1 vs. 0.9) in first-line treatment of mCRC.  PSA portends that Bev+FOLFIRI is dominant over Cet+FOLFIRI (93,44% of iterations Bev+FOLFIRI prolonged OS, being less costly).  CONCLUSIONS: Based on current available data, analysis suggest Bev+FOLFIRI presents lower costs and better efficacy than Cet+FOLFIRI for treatment of first-line mCRC from a private payer perspective in Brazil.