Ecstasy is a synthetic amphetamine used as a recreational drug. 62 patients with acute liver failure seen in a three-year period were reviewed. Viral hepatitis was diagnosed in 30, toxic hepatitis in 11 (anti-tuberculous agents in 6, acetaminophen overdose in one, halothane in 2 and amainita poisoning in 1, etc.), miscellaneous causes in 6, and undetermined origin in 10. Of the latter group, five were associated with ecstasy consumption, representing 5 of 16 due to toxic agents (31%). They presented after a short prodrome with abdominal pain and jaundice. All had ALT >2500 (u/l), hypoglycemia, and protime <50%. Latency was 1-2 weeks after ingestion. None developed encephalopathy. Dosage varies from one tablet to regular use for weeks or months. One positive rechallenge occurred. In Spain, ecstasy accounts for the majority of severe hepatitis cases of toxic origin.