Background: Ecstasy use is generally chosen by adolescents and young adults for its entactogenic properties (the production of feelings of empathy, love, and emotional closeness to others.) Despite this desired and frequently realized outcome, Ecstasy use has often resulted in the genesis of psychotic symptoms and aggressive behaviors, particularly after chronic and/or intensive use. Methods: To explore the negative consequences of Ecstasy use and to examine the aggressive nature oftentimes seen in many Ecstasy users we employed a case-control study model. We compared, by means of validated psychometric tests, the psychopathological symptoms (BPRS), the aggressiveness (OAS) and the social adjustment (DSM-GAF) of psychotic patients with (n = 23) and without (n = 46) recent user of Ecstasy, during their first psychotic episode and hospitalization. All 23 Ecstasy users were Ecstasy users only. Results: Almost all of the psychotic symptoms were of similar severity in both groups. Blunted affect was milder in users than in non-users, whereas hostility and aggressive behavior was significantly more severe in users than in non-users. Conclusions: psychosis with a high level of aggressiveness and violence constitutes an important ‘side-effect’ that surely runs counter to the expected entactogenic action of Ecstasy. At a patient psycho-educational level, this study suggests that the use of Ecstasy may be counterproductive with respect to user expectations.