Recently, intranasal dexmedetomidine (DEX) has been reported to be effective as a preanesthetic medication, mostly in healthy pediatric patients. We attempted to administer intranasal DEX premedication in this case to an adult patient with intellectual disability who previously had difficulty tolerating premedication with oral midazolam. Using an intranasal atomization delivery device (MAD Nasal, Teleflex), we administered 1.5 µg/kg of DEX intranasally and were able to achieve adequate sedation, which facilitated a smooth mask induction of general anesthesia with sevoflurane. Premedication with intranasal DEX may be a useful method for enabling induction of general anesthesia in adult patients with intellectual disabilities.