This article discusses the nature of psychiatric evidence in Icelandic criminal proceedings and presents findings from an investigation of the role of amnesia, malingering and overcontrolled hostility among different types of offenders. Amnesia was most common in homicide cases, and was almost invariably associated with alcohol intoxication. An unexpectedly high rate of overcontrolled hostility was found among sex offenders, which may have important theoretical and clinical implications. The results indicate that deliberate faking of an intellectual deficit on psychometric tests occurs rarely in a forensic context.