Asperger's Syndrome is a pervasive developmental disorder on the Autistic spectrum. Antisocial behaviour is frequently described as an accompaniment of Asperger's Syndrome although the strength of any association between Asperger's Syndrome and offending remains uncertain. This paper presents five patients with Asperger's Syndrome with a history of offending. For each of them the offending is understandable in the context of the disorder. The specific and general issues raised by these cases in relation to Fitness to Plead and Legal Insanity are considered. Offenders with Asperger's Syndrome have deficits that raise the likelihood that their disorder will render them unfit or be of exculpatory value.