The American Academy of Paediatrics endorses obtaining assent when prescribing medications for attention-deficit/hyperactivity disorder (ADHD) in older children whenever possible. Studies indicate the concept of assent may not be well understood by clinicians, possibly effecting effective and widespread implementation. We argue that though the concept of assent continues to evolve, it is critical in the context of patient-centred care, shared decision-making and in supporting minors’ transition to adulthood. Based on the principle of respect for young persons, we argue that obtaining assent is an ethical imperative when prescribing medication for ADHD. We highlight the instrumental benefits of obtaining assent in the paediatric clinical encounter when prescribing medications for treatment of ADHD.