Belgian and regional government attach an increasing importance to 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 discussed with special emphasis on discount rates and the value of human lifes. Three types of seat belt reminder systems are studied considered. Implementation costs of € 63,00, € 127,00 and € 150,00 are applied. If one considers commonly used dicount rates, one can observe the following at each of the different rates: - if the least expensive seat belt reminder system would be chosen, the project would already be beneficial when an effectiveness of 5% would be reached - if the seat belt reminder system costing € 127,00 would be chosen, an effectiveness of 10% would already make the system beneficial - the most expensive system would only become beneficial for society when an effectivness between 10% and 15% would be reached. - an increase in seat belt wearing amongst non-seat belt wearing drivers and passengers of 13% is necessary to make the seat belt reminder system beneficial from a social point of view.Research Rapport RA-2003-16, Diepenbeek: Steunpunt Verkeersveiligheid, 26 pag.