All the studies on the cost benefits of drug treatment reviewed by Cartwright in this issue suggest benefits outweigh costs by some margin. What lessons does this review of mainly American data have for European policy makers? Drug treatments are associated with a wide range of consequences outside the health sector and there are considerable differences in treatment regimes across countries. This could well influence results. There are also considerable differences in methodologies used across available studies and many lack strong study designs. An interesting feature is the lack of valuation of individual drug users benefits, does this imply that policy makers in the US do not care about drug misusers. Would the situation be the same in Europe or other parts of the world? There is a lot of research to be done and perhaps specific guidelines are required to ensure economic evaluations in this area can be used to guide policy decisions with more confidence.