Paediatric Obsessive Compulsive Disorder (OCD) is still under-diagnosed, despite significant advances made in identifying obsessive-compulsive symptoms. The authors report a case of adolescent-onset OCD presenting as a mixed dissociative disorder. The drug assisted interview provided a breakthrough in revising the correct diagnosis of the clinical condition. The psychopathology of the patient contains sexual and aggressive obsessions without any compulsions. Adolescent OCD can present as dissociative disorders and a thiopentone interview can be helpful in revealing the distress associated with OCD.