A seven-year-old boy presented with a right-side mandibular luxation resulting from an acute unilateral dystonia of the masticatory muscles. Repositioning took place under a general anaesthetic. The luxation recurred the same day. Once again the jaw was repositioned under a general anaesthetic. In view of the rarity of jaw dislocation in someone so young it was assumed that it could have been caused by a dystonia possibly resulting from the patient's medication. The patient was known to have Attention Deficit Hyperactivity Disorder (ADHD). To treat the condition, the patient's psychiatrist had prescribed 1 mg risperidone daily for one year and 10 mg methylphenidate daily for two years. Following the discussion with the psychiatrist, the patient was taken off both of these drugs and instead was prescribed oxazepam. So far the luxation has not recurred.