Sixty male non-psychotic forensic psychiatric patients (aged 16-35 years) were studied after they completed their ordinary forensic psychiatric assessment (FPA). The prevalence of flunitrazepam (FZ) abuse was investigated by using both structured and in-depth interviews with the objective of studying the relationship between the abuse and personality traits. The patient's characteristics, DSM-IV disorders, and actual sentences were obtained by studying their files. In order to obtain measures on their personality traits, self-report inventories were administered to the patients. Eighteen out of 60 patients were FZ abusers, but only 4 of them received a diagnosis related to the FZ abuse during the ordinary FPA. In almost all cases, however, indications of the FZ abuse were found in the files. No differences in personality traits were found between the groups. The frequency of previous admissions to an FPA and actual sentences of robbery, weapons offenses, narcotic-related offenses, and other crimes (such as theft) among the FZ abusers deviated significantly from forensic non-FZ abusers. Therefore, the FZ abuse per se might be more responsible for their tendency to commit crimes characterized by danger and thrill-seeking (such as robbery, weapons offences, and theft) than personality. The most important conclusion is that assessment of FZ abuse is needed in forensic psychiatry.