3,4-methylenedioxymethamphetamine (MDMA or Ecstasy) has been implicated in the onset of a number of psychological disorders and associated with a number of psychiatric symptoms that have persisted after cessation of the drug. This paper is a review of the published psychiatric case studies from the last 10 years involving MDMA. Only 24% of patients had a previous psychiatric history and 34% had a psychiatric illness amongst first degree relatives. The percentage of patients not having had a personal or family history of psychiatric illness and the temporal relationship between MDMA ingestion and the experience of recurring symptoms strongly suggest a causal relationship between the drug and neuropsychiatric manifestations. Further supporting evidence comes from several studies using non-clinical samples. Ecstasy users that don't present themselves in healthcare settings as having clinical symptoms have significantly higher scores on certain subscales of the SCL-90 compared with Ecstasy-naive controls, with higher pathology scores in heavier Ecstasy users. The full-blown psychiatric cases may represent the broad end of this problematic spectrum. Copyright © 2001 John Wiley & Sons, Ltd.