[en] The aim of this report is to introduce readers to methods of cost-effectiveness analysis and their application in risk reduction, especially in connection with the energy-producing industries. The background to the assessment of risk and the problems in estimating it quantitatively are outlined. The methodology of cost-effectiveness analysis is then described, particular attention being given to the way in which results are derived and the overall use that can be made of them. This is followed by a discussion of quantitative applications and an outline of the methods that may be used to derive estimates both of risk and the cost of reducing it. The use of cost-effectiveness analysis is illustrated in an appendix, which gives as a worked example a case study on the reduction of public risk associated with radioactive releases during normal operation of a PWR. After drawing some general conclusions the report recommends that such analyses should normally be used as an aid to risk management whenever several alternative risk reduction measures are under consideration