"Ecstasy" (3,4-methylenedioxymethamphetamine, MDMA) is a prototype of a class of amphetamine derivatives that selectively destroy serotonergic neurons in several brain regions of various species, including, most probably, humans. Due to its psychostimulant and psychodelic effects, "Ecstasy" has been increasingly abused, especially in association with the "Rave" (sub)culture. However, it is not an innocent stimulant. At least 30 cases of severe psychiatric disturbances (chronic psychoses, panic disorders, suicides) induced by recreational doses of "Ecstasy" have been reported during the past 10 years in periodicals included in MEDLINE data base. Moreover, about 70 cases of severe systemic intoxication in young, otherwise healthy individuals, characterized by hyperthermia, arrhythmias and blood pressure disturbances, disseminated intravascular coagulation, rhabdomyolysis and acute renal failure, have also been reported. Despite the fact that the patients were treated at the intensive care units, the mortality exceeded 40%. Furthermore, about 20 cases of acute or recurrent non-infective hepatitis, some of which with lethal outcome, have been described as well.