Biodiversity underpins most economic activities in Seychelles, and loss of biodiversity as a result of Invasive Alien Species (IAS) could result in major negative economic impacts for the country. This study assessed the value of impacts of IAS on biodiversity, natural resources and the national economy, using total economic value (TEV) principles, and conducted a Cost-Benefit Analysis of IAS management in Seychelles, taking into account TEV. Using a survey questionnaire, the contingent valuation method was used to obtain a Willingness to Pay (WTP) for a scenario to protect biodiversity at risk from IAS. Seychelles currently spends some US $0.79 per person per year on quarantine measures targeting IAS at the border. We found that economic damage associated with only 4 IAS approximately amount to US $21 million per year while only US $0.25 million per year is spent on their control. This indicates that IAS are causing significant economic impact in Seychelles. Tourists’ responses to the questionnaire indicated a mean WTP of US $52-US $58 on top of their usual expenditures to fund conservation policy. Comparing the benefits from eradication with the costs involved gives a benefit-cost ratio greater than unity, indicating that the policy of eradicating IAS is economically justified. However, there is a long way to go before the resources devoted to the problem will be in proportion to the risks.