A total of 130 patients, 15- to 22- years-old (127 males and 3 females), were evaluated at the Forensic Psychiatric Department in Stockholm from 1990 through 1995; they had committed serious offenses, mostly of a violent nature. A total of 126 of the 130 cases were included in the study due to the absence of FPI records for 4 of the cases. Case report sheets were prepared and retrospective neuropsychiatric DSM-IV diagnoses were made by two of the authors of this report. For best-estimated diagnoses, the case report sheets were then submitted to another of the authors, a child neuropsychiatrist with expertise in this area. Fifteen percent of the subjects were given a definite diagnosis of ADHD (attention-deficit/hyperactivity disorder), and another 15 percent had PDD not otherwise specified; 3 percent had Asperger syndrome. Autistic disorder was not found in any case. Tourette syndrome occurred in 2 percent of the cases. The rate of PDD was particularly striking. Neuropsychiatric diagnoses had been determined in the FPI in only a few cases. The authors advise that because there are no prospective studies with more methodologically rigorous designs to compare with the current study, the findings must be viewed with some skepticism; however, the authors believe that the findings of this study reflect even higher rates of true disorder in young forensic psychiatric patients who have committed serious offenses. What is needed next is a systematic prospective study of autistic-type problems and attention disorders in cohorts of forensic psychiatric patients and in other forensic populations, using the most appropriate and up-to-date methodology and relevant control groups. 5 tables and 43 references