A Norwegian government publication (1) claims a prevalence of around 50% of Antisocial Personality Disorder (APD) in a small group of male detainees on preventive detention. The present study population is recruited from more or less the same population as those among whom a 50% prevalence of APD has been claimed (1). Norwegian forensic investigators rarely (17%) apply psychometric tools to confirm their clinical diagnosis (2).

To confirm the diagnosis of APD applying SCID axis II. Methods: Fifty six inmates were available at the prison. Twenty eight were willing to participate (50%). Two were excluded. Thus, 26 (46%) inmates participated. DSM IV, SCID axis II was applied.

None of the 26/56 matched the APD criteria, mainly failing to fulfil the diagnosis of Conduct Disorder (CD) before the age of 15 years. All the inmates had a history of antisocial behaviour.

To explain the claim of around 50% APD in view of the present results, close to 100% APD should be found among the remaning thirty non-participating inmates. We consider this unlikely.

A diagnosis of APD based on the history of antisocial behaviour alone represents a pitfall. Lack of quality assurance could lead to false positive diagnosis. The need for a standardized approach and quality assurance in Norwegian forensic psychiatric evaluations seems nevessary to avoid false positive diagnosis.