OBJECTIVES: The FIRE-3 phase III clinical trial demonstrated the marked advantage of prolonging the median overall survival (OS) of patients with final RAS wild-type left-sided metastatic colorectal cancer (mCRC) by 38.3 months after treatment with irinotecan, fluorouracil and leucovorin (FOLFIRI) plus cetuximab and by 28.0 months after treatment with FOLFIRI plus bevacizumab. However, the substantial cost increase and economic impact of using cetuximab imposes a considerable burden on patients and society. In this study, we used FIRE-3 data to estimate the cost-effectiveness of cetuximab and bevacizumab treatment in patients with left-sided RAS wild-type mCRC in China. METHODS: A Markov model based on the data collected in the FIRE-3 trial was developed to investigate the cost-effectiveness of treating patients with FOLFIRI plus either cetuximab or bevacizumab. Costs, quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICER) were calculated over a lifetime horizon. One-way and probabilistic sensitivity analyses were performed by varying potentially modifiable parameters. RESULTS: In our analysis, the total treatment costs in the bevacizumab and cetuximab groups were $92,549.31 and $94,987.31, respectively, and the QALYs gained were 1.79 and 2.30. In the base-case analysis, compared with bevacizumab, left-sided RAS wild-type patients receiving cetuximab gained 0.51 more QALYs at an ICER of $4,755.48/QALY ($3,166.23/LY). The one-way sensitivity analysis showed that the most influential parameter was the cost of cetuximab. The probabilistic sensitivity analysis predicted a 90.4% likelihood that the cetuximab group is cost-effective. CONCLUSIONS: Our analysis suggests that treatment with FOLFIRI plus cetuximab in Chinese patients with left-sided RAS wild-type mCRC may improve health outcomes and use financial resources more efficiently than FOLFIRI plus bevacizumab. This information may be useful to clinicians, payers, and policymakers in making treatment and resource allocation decisions from the perspective of the Chinese health care system.