OBJECTIVES: To evaluate the cost-effectiveness of a vision screening program for early detection of preschool children with amblyopia in Taipei City, Taiwan. METHODS: A decision analytic model was established to simulate the natural history of amblyopia in the context of Health Bureau of Taipei City Government. A societal perspective was undertaken to perform the cost-utility analysis and cost-benefit analysis. Cumulative quality-adjusted life years, lifetime benefits, and lifetime costs for the following two strategies were compared: 1) A vision screening program was implemented toward preschool children aged 4-6; 2) No vision screening program. Net benefits and incremental cost-effectiveness ratio (ICER) were calculated to assess whether vision screening programs is cost-effective and cost-benefit. All costs and outcomes were discounted at an annual rate of 3%. One-way sensitivity analysis and probabilistic sensitivity analysis were performed to account for the uncertainty of the parameters. RESULTS: The model predicted the discounted average life-time QALYs were 29.2067 QALYs per child for strategy 1, and 29.2051 QALYs for strategy 2. The discounted average total lifetime costs were NT$723.9 and NT$593.6 per child for strategy 1 and strategy 2, respectively. ICER for the screening strategy was NT$80,932/QALY. The net social benefits was NT$160.7 per child and the vision screening program for preschool children could potentially bring approximately NT$6,900,297 net benefit to the society. Results were most sensitive to the prevalence rate of amblyopic. The vision screening strategy was always preferred when a threshold of willingness-to-pay for a QALY was >= NT$50,000. CONCLUSIONS: In comparison with no screening program, ICER for the vision screening program was found to be less than NT$555,760 (three times GDP per capita in 2007 in Taiwan). The vision screening program for preschool children aged 4-6 were cost-effective in Taipei City, Taiwan.