OBJECTIVES: The purpose of this analysis was to examine the economic efficiency of treating metastatic colorectal cancer (mCRC) with XELOX +/- Bevacizumab every three weeks versus FOLFOX-4 +/- Bevacizumab every two weeks as first-line treatment.METHODS: The decision model was developed from the social perspective. The mean annual total cost per patient treated was estimated considering the annual drug costs, the annual cost associated with the drug administration and the annual cost to treat the adverse effects induced by each regime. We include the social costs derived from the time that the patient incurred in the chemotherapy administration process and the time consumed by travelling to the health care centre. According to the trial, the treatments with XELOX and FOLFOX-4 have a similar effectiveness profiles.RESULTS: Total direct annual cost from the perspective of the health care payer was €639 inferior with XELOX when compared with FOLFOX-4 and €1887 inferior when it was compared [XELOX + Bevacizumab] with [FOLFOX-4 + Bevacizumab]. Including indirect costs, the regimes with XELOX presented a lower cost of €1534 (without bevacizumab) and €3.003 (with bevacizumab) when they are compared with the respective regimes with FOLFOX-4.CONCLUSIONS: The smaller annual cost of the chemotherapy based on XELOX it is due to a relatively smaller costs associated to the administration of oral capecitabine; the implantation of a central venous access device which is not needed in the great majority of patients following the XELOX regimes; and for the smaller number of administration cycles throughout the 48 weeks period under study.