Williams syndrome is a rare genetic disorder with a frequency of one per 20,000-50,000 live births. It is caused by a deletion of one elastin allele located within chromosome subunit 7q11.23 (long arm). This syndrome is frequently accompanied by congenital heart disease, facial anomalies, and mental retardation and as a result, anesthetic management may be complicated by hemodynamic instability and difficult intubation. Also, as it was reported that this disease is associated with malignant hyperthermia, careful anesthetic selection is required. We experienced the anesthetic management of a 3-year-old girl with Williams syndrome who received dental treatment for severe dental caries under general anesthesia, and of a 4-year-old girl underwent aortoplasty for supravalvular aortic stenosis. Airway management and tracheal intubation was accomplished successfully in both patients. For anesthetic management, propofol, fentanyl and rocuronium, and fentanyl, isoflurane and vecuronium were used in the first and second patients, respectively. Surgeries were performed uneventfully in both cases, and the patients were discharged without complication.