This guideline report concentrates on the operational aspects of applying CBA to evaluate projects when there are significant environmental impacts. It is addressed to the need for officials and planners in developing countries to have an overview of the subject and, perhaps even more important, to have a quick review of the operational problems of applying the technique to environmental and health impact assessment. Essential economic concepts relating to the application of CBA to human health and environmental problems are discussed. Examples and case studies are included to illustrate how CBA has been used for a range of problems.