This Manual is a revised edition of the Treatment demand indicator (TDI) protocol version 2.0 and presents updated guidelines for reporting data on people entering drug treatment in Europe. The TDI is one of five key epidemiological indicators which provide a common European methodology for collecting and reporting core data on the number and profiles of those entering specialised drug treatment each year. TDI data are routinely used in EMCDDA analysis of the drug situation in Europe, helping to identify trends and patterns in problem drug use and to assess the use and uptake of treatment facilities.