Many dentists have faced children that display the gagging reflex during dental treatment, making any procedure difficult. This case presents the proposition that these gagging attacks may be of psychogenic origin. This is a boy showed extremely psychogenic gagging behavior. His past history showed that he experienced syncope and vomiting when facing unpleasant situations or when desiring parent's attention. Neurological exam showed that there was no sign of neurotic anomaly. Concluded from the medical history, it was supposed as psychogenic origin. Systemic desensitization and waking hypnosis (intensively emphasizing that he wouldn't vomit) were used from the first appointment. Also he was told that vomiting would keep mother away from the operating room. During the following appointments, the patient was less nervous and less gagging was exhibited. By the end of dental treatment course, the patient behaved well and no vomiting was noticed. After 2 years, he came back for follow-up and was doing well. Children frequently use gagging and vomiting as an excuse to avoid dental treatment. Differential diagnosis for somatogenic and psychogenic gagging is the key to manage the pediatric patients successfully. If it is diagnosed with psychogenic gagging problem, the dentists can utilize systemic desensitization and waking hypnosis to increase patients' confidence and successfully complete the dental treatment. (Taiwan J Pediatr Dent 2(4): 110-115, 2002)