It is estimated that over 1 million people receive treatment for drug-related problems in the European Union every year. With shrinking public budgets, increasing pressure on health systems, changes in the drugs used and the need to provide on-going care to chronic cases, what is the real cost of drug treatment in Europe? In collaboration with experts from around the globe, the EMCDDA has compiled this analytical report, the first of its kind, to present the current practices used for estimating drug treatment costs in order to help fill the knowledge gap.