Cleft lip ± cleft palate (CL/P) and cleft palate (CP) are the most common congenital craniofacial abnormalities with an estimated prevalence of 1:690 in the United States. Both conditions can be divided into syndromic (associated with other abnormalities) and non-syndromic (isolated), with about 70% of the cases with CL/P and 50% of the cases with CP being non-syndromic. In the United States, the prevalence of isolated cleft lip (CL) is 1:3226 live births, of isolated cleft lip and palate (CL + CP) 1:1786, and of isolated CP 1:1695 live births. While the prevalence of CP is the same in different countries and ethnic backgrounds, the incidence of CL/P differs according to race, ethnic background, environmental exposures, socioeconomic status, and geographical origin. Thus, in the United States, the prevalence of isolated CL/P is lowest among blacks and highest among American Indians. CL/P is also very high among the First Nations population in British Columbia, Canada [1/300]. Furthermore, while CP is more common in females, CL/P is more common in males.