The co-occurrence of congenital central hypoventilation syndrome (CCHS) and Hirschsprung's disease (HD) is termed Haddad syndrome, which is an extremely rare disorder. It was reported first by Haddad in 1978 and there are approximately 60 cases reported in the worldwide literature. Recent studies described that congenital central hypoventilation syndrome had deep relation to the mutation of the PHOX2B gene in its diagnosis and phenotype. This article presents a case report: Dental treatment of a 3-year-old male patient with Haddad syndrome under outpatient general anesthesia. The special considerations of dental care, especially caries treatment for the patient with Haddad syndrome are discussed.