With an increasing movement towards cost saving in the health sector, preventive medicine must also be judged according to its economic viability. The fact that prevention can autofinance itself is suggested by the results of a cost/benefit analysis of chemoprophylaxis of Falciparum malaria with Mefloquin among travellers in Kenya. Out of the whole group of travellers analysed by means of an interview-based test (Malpro-Study), the costs in the case of both Switzerland and the Federal German Republic were lower for those people who had undergone Mefloquin-prophylaxis than for those who had not. In this way the prophylaxis not only compensates the required outlay but also results in an overall benefit in macroeconomic terms. Therefore economically based opposition to the prophylaxis of malaria with Mefloquin for short stays in high-risk countries is not justified.