The conceptualization of a spectrum of obsessive-compulsive disorders, comprising disorders such as OCD, body dysmorphic disorder, substance abuse, pathological gambling and autism, is increasingly accepted. These disorders share obsessive-compulsive features and show similarities in patient characteristics, course of illness, comorbid disorders and neurobiology. Recent research suggests the possibility that autism spectrum disorder (ASD) in its milder forms may be clinically important among a proportion of patients with OCD. OCD with comorbid ASD should be recognized as a valid OCD subtype. A strange personality, with paranoid, schizotypal, avoidant or obsessive-compulsive traits, may indicate these autistic dimensions in OCD patients. In ASD patients, arguments often arise amongst nosologists, as to what constitutes their repetitive, ritualistic, quasi compulsive behaviour. At a descriptive behavioural level, the majority of ASD patients experience their symptoms as egosyntonic. Nevertheless, they frequently share the same egodystonicity as their genuine OCD counterparts. It has been found that adults with ASD are more likely to show repetitive ordering, checking, lining up, hoarding and touching, as opposed to classic OCD. Their obsessive thoughts are less likely to involve the usual themes of aggression, religion and sex. In general compulsions and rituals seem to be more common than pure obsessions. OCD like behaviours are often conceptualized as an epiphenomenon that is associated with the diagnosis of ASD. Several case vignettes will be presented to provide insight into how neuropsychological phenotypes constitute a workable framework to conceptualise OCD like behaviours as manifested in ASD.