Epidemiological research and Substance Abuse Warning Systems point to a sharp increase in the use of "Ecstasy" (MDMA), as well as to structural changes in the drug scene in and outside Europe. For some consumers, "Ecstasy" opens the door to the abuse of other illegal substances. Since the mid-eighties psychiatric complications and consequences of the abuse of MDMA have been reported in at least 48 cases. It is necessary to differentiate between acute psychiatric complications, which subside completely when the level of intoxication comes down, toxic psychoses and long-term psychiatric diseases as a consequence of substance abuse. The latter involve atypical and paranoid psychoses, depressions, panic disorders, depersonalisation and behavioural disorders. Convulsive seizures are among the most common problems involving the central nervous system. Furthermore, there have been reports on cerebrovascular accidents and intracranial haemorrhages. Literature reports on at least 53 cases of medical complications in abusers of MDMA, 14 of which came to a lethal end. Research still blatantly lacks prospective epidemiological and clinical studies on a sufficiently large scale to identify different developments of dependency and predictors of harmful and unhealthy consumption.