A retrospective study of the prevalence of child neuropsychiatric disorders was done involving pervasive developmental disorder (PDD), attention-deficit/hyperactivity disorder (ADHD), and Tourette syndrome in young offenders (15-22 years, n = 126) consecutively referred for presentencing forensic psychiatric investigation (FPI) in Stockholm, Sweden. Most offenders were referred for FPI because of serious offenses. Case report sheets were prepared, and retrospective neuropsychiatric DSM IV diagnoses were made by the first two authors. For best-estimated diagnoses, the case report sheets were then submitted to the fifth author, a child neuropsychiatrist with expertise in this area. Fifteen percent of the subjects had a definite diagnosis of ADHD, and another 15 percent had PDD, including 12 percent PDD not otherwise specified (NOS) and 3 percent Asperger syndrome. Autistic disorder was not found in any case. Tourette syndrome occurred in two percent of the cases. The rate of PDD is particularly striking. Neuropsychiatric diagnoses had been determined in the FPI in only a few cases. The contribution of constitutional problems to later criminal development may have been underestimated.