Asperger's Syndrome is one of the diagnostic subcategories of pervasive developmental disorders. It is characterized by a defect in reciprocal social interaction, lack of empathy for others and poor non-verbal communication. Antisocial acts, including aggression and sexual offense, are not considered to be common in this disorder. We describe an adolescent with Asperger's Syndrome whose main problems are his violence and sexual offenses. We assume that these symptoms are secondary to his diagnosis of Asperger's as a manifestation of his difficulties with the "theory of mind" of others. This atypical case report is in contrast with the low prevalence of aggression and sexual offense in Asperger's, as reported in the literature. We discuss the reasons for this low prevalence. Our conclusions are based on one case history and a literature review. We call for further research in this field.