Belgian and regional government attaches increasing importane to the matter of road safety. Economic analyses improve the allocation of scarce resources to improve road safety. Two types of eonomic analysis, cost-benefit analysis and cost-effectiveness are disussed. A comparison of costs and benefits at different moments in time discussed, with a focus on the discount rate which should be applied in cost-benefit analysis. The difficulties of valuing the victims of road crashes are discussed. It is stressed that international results can't be copied literally for belgian research. A case study is executed in which a cost-benefit analysis for a seat belt reminder system is performed. A 10 year period is taken into account. The unit costs for the seat belt reminder system are taken from australian research. Three types of seat belt reminder systems are considered, each with a different level of extortion. Implementation costs of € 63,00, € 127,00 and € 150,00 are applied. Because it is assumed that the number of accidents doesn't change, no incremental external costs (for congestion, environmental damage of infrastrucutre) occur. Costs and benefits for different levels of effectiveness are calculated. It is assumed that the total number of accidents doesn't change, but the ratio between persons who do buckle up and persons who don't buckle up does change due to the seat belt reminder system. A value of 5,703 million euro for a fatality s assumed. Seriously and slightly injured are valued at 0,771 million euro and 0,183 million euro respectively.The net present value of the costs, for a period of 10 years is shown in the table below. NPV Unit costs Discount rate 4% 5% 7% 15% 63 Euro 285 274 254 195 127 Euro 574 552 512 393 150 Euro 678 652 604 464 The net present value of the benefits for the same period, at different rates of effectiveness and different discount rates is shown below. Discount rate Effectiveness 4% 5% 7% 15% 5% 312 295 266 180 10% 624 591 531 361 15% 936 886 796 542 20% 1.248 1.181 1.062 723 25% ...