© 2020 Elsevier Inc. All rights reserved. Congenital heart defects have always had a special place of significance among birth defects for clinical geneticists. They are often the first anomaly to present in a child with an underlying syndrome, and, as many are life-threatening, they also typically command the greatest attention. This chapter will provide an overview of congenital heart defects from a perspective most relevant to the clinical geneticist. Cardiac embryology will be reviewed with emphasis on known genes and associated heart defects. An approach to the patient with a congenital heart defect will be suggested. Common genetic syndromes with cardiac defects as major manifestations (categorized by etiology: chromosomal/aneuploidy syndromes, segmental chromosomal deletion/duplication syndromes, single-gene mutations, and teratogenic) will be highlighted. Issues unique to the adult patient with congenital heart defects will be discussed as well as information regarding recurrence risks. In addition, tables of well-researched syndromes and genes associated with isolated and syndromic heart defects will be provided as a reference.