This study examines the clinical characteristics of patients with methamphetamine-induced organic mental disorders that were seen in a psychiatric emergency service. This was a highly dysfunctional group, requiring psychiatric hospitalization in 90% of cases. The most consistent clinical feature was the presence of an organic delusional syndrome, with paranoid ideation and hallucinations. Methamphetamine abusers were also unique in their propensity for violence; 43% of the group had clear histories of aggression towards others. The increasing use of methamphetamine together with its ability to produce severe dysfunction is a major concern of professionals and communities alike in terms of treatment [corrected].