Rubinstein-Taybi syndrome (RTS) is a human genetic disorder characterized by mental retardation and physical abnormalities including broad thumbs, big and broad toes, short stature, and craniofacial anomalies. The oral manifestations include small oral opening, pouting lower lip, retro/micrognathia. and higher arched, narrow palace. The purpose of this case report was to demonstrate the complicated dental treatment of a 12-year-old, developmentally disabled girl, living with a foster family, who suffered from RTS, extensive caries, and very poor oral hygiene. The patient demonstrated total lack of cooperation. The dental treatment had been carried out under general anesthesia (GA). Possible problems during GA in such patients are described. Fiberoptic video-assisted bronchoscope was prepared for the GA in case of air-way emergency and/or difficult intubation. The GA process was uneventful, despite the extensive treatment delivered to the patient. Prospects for future good oral and dental status in this patient are questionable because of her extreme lack of cooperation.