The present study examined the characteristics and the possible psychopathological consequences of ecstasy (MDMA, 3,4-methylenedioxymethamphetamine) use. One hundred and fifty consecutive patients, presenting to the Padova (Italy) Addiction Treatment Unit and who had taken ecstasy on at least one occasion, were examined and studied using a semi-structured interview. Ninety-five percent of the patients had experimented with another drug of abuse at least once in their lifetime. Ecstasy was mainly self-administered at disco clubs, and reported acute psychoactive effects confirmed previous reports. Fifty-three percent of the total sample were found to be affected by one or more psychopathological problems; the most frequent were depression, psychotic disorders, cognitive disturbances, bulimic episodes, impulse control disorders, panic disorders, social phobia. Those who were free from any psychopathological problem, compared to the others, had taken a smaller number of MDMA tablets in their lifetime, for a shorter duration and with a lower frequency. Again, they were less likely to have used alcohol together with ecstasy but more likely to have used opiates. Longer-term, larger dosage (acute or cumulative) MDMA consumers were found to be at high risk of developing psychopathological disturbances. The results are discussed, taking into account both the ecstasy suggested serotonin (5-hydroxytryptamine) neurotoxicity and the various methodological issues pertaining to this kind of large-scale clinical study describing people for whom MDMA is far from being the only drug of abuse.