Two case reports of ecstasy abuse and its serious neuropsychiatric complications are presented. The first patient developed a florid paranoid psychosis resembling schizophrenia after repeated long-term recreational ecstasy abuse, and significant alterations with intermittent paroxysmal discharges were found in his electroencephalogram. The second patient showed an atypical paranoid psychosis with Fregoli syndrome and a series of complex-partial epileptic seizures with secondary generalization after a first single ecstasy dose. Both subjects presented considerable vulnerability; the first a minimal brain dysfunction after perinatal asphyxia and a persisting attention deficit/hyperactivity disorder, the second a long-lasting opioid addiction. In vulnerable individuals, dose-independent ecstasy abuse can lead to unpredictable and potentially dangerous neuropsychiatric sequelae which require proper initial assessment and adequate treatment.