Samenvatting
Results of an inventory of completed research and studies on the use of illegal drugs are presented. Definitions of the problematical use of hard- drugs and its related problems, as well as the typologies of the hard- drug users in the different studies, are presented. In the second part the use of soft drugs is described shortly. The third part discusses the use of hard drugs in more detail and presents data on the demand for and the offer of professional assistance.