OBJECTIVES To model expected mean incremental costs and life expectancy of adding bevacizumab (bev) to an irinotecan plus infusional 5-fluorouracil/leucovorin (5-FU/LV) regimen (FOLFIRI) for the first-line treatment of patients with metastatic colorectal cancer (MCRC) in Sweden. METHODS A 3-health-state model explored the effects of adding bev treatment to an existing FOLFIRI-based regimen. The model structure was based on one published by National Institute for Health and Clinical Excellence (NICE) UK, which applies to guidelines established by the Swedish Pharmaceutical and Dental Benefits Board. Progression-free (PFS) and overall survival (OS) data are derived from clinical trials comparing bev+irinotecan and 5-FU/LV (IFL) with IFL alone. The impact on OS for bev+FOLFIRI was included through an indirect comparison of hazard ratios (HRs) between bev+mIFL versus bev+FOLFIRI (HR for death: 1.79; 95%CI: 1.12–2.88). Treatment effect for bev+FOLFIRI was maintained during the 40-month clinical follow-up. The FOLFIRI PFS was created by applying the HR from IFL versus FOLFIRI (HR for progression or death: 1.51, 95%CI: 1.16–1.97) to the IFL PFS. Outcomes included life years, QALYs, direct costs and incremental cost-effectiveness ratios (ICERs). A life-time horizon (eight years) was used. Cost and outcomes were discounted by 3% per annum. RESULTS The estimated mean life expectancy for bev+FOLFIRI-treated patients was 2.64 years (discounted; 2.77 years undiscounted) versus 1.58 years (discounted; 1.63 years undiscounted) in the FOLFIRI arm. The discounted costs in the 2 arms were 525,404 SEK and 245,775 SEK, respectively. The discounted ICER was 264,689 SEK/life-year gained and 428,519 SEK/QALY gained. Sensitivity analysis on key variables showed that assumptions of size (HR) of treatment effect and duration of treatment effect were the most critical factors for the ICER. CONCLUSIONS Bev+FOLFIRI versus current FOLFIRI-based treatment regimens for MCRC is predicted to increase survival for these patients and also be a cost-effective treatment option in Sweden.