JCNRJournal of Clinical and Nursing Research2208-36852208-3693Bio-Byword Scientific Publishing Pty. Ltd.10.26689/jcnr.v2i1.299Articlehttps://artdesignp.com/journal/JCNR/2/1/10.26689/jcnr.v2i1.299ChandradasaMiyuru2018212018-01-31Background: Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder manifesting in early life. These children are more vulnerable to sexual abuse as victims and offenders. This is a case report of a teenager with previously undiagnosed ADHD presenting with an alleged act of sexual offending.Case report: According to the 14-year-old accused, he has engaged  in  penetrative  anal  intercourse  with  another schoolmate. that similar past incidents had involved a teenage malerelative and insertion of foreign bodies to his anus repeatedly by him. On assessment the accused had features of inattention, such as difficulty in sustaining attention, failing to finish work and features of impulsivity, such as difficulty waiting for his turn and intruding on others. He was diagnosed with ADHD according to Diagnostic and Statistical Manual of Mental disorders (DSM 5) clinical criteria which were supported by the Sinhalese adaptation of the Swanson, Nolan and Pelham questionnaire. The assessment of the non-verbal intelligence was in the normal range, but his school performance was far below the average.Discussion:  Undiagnosed ADHD contributes to academic impairment and inappropriate sexual behaviour. It is possible that the described adolescent’s impulsiveness and inattention contributed to his academic failure and risky sexual behaviour. Early detection and proper management of this disorder may have reduced the risk of such behaviour in him.