Labial and/or palatine clefts are an interest in example of the interaction between genetic and environmental factors. The OFC1 gene, localized on 6p24.3 would play a primary role in the development of labial and/or palatine clefts while the OFC2 (2p13), OFC3 (19p13.2) and RARA (17q21.1) would play a role in modifying genetic susceptibility. Different environmental, nutritional and toxic factors (alcohol, tobacco, drugs...) could also directly contribute one-third of these oral clefts. Identification of subjects at risk of having a child with labial and/or palatine cleft on the basis of both phenotypic and genotypic factors would be most helpful in recognizing environmental factors triggering their development, a first step towards prevention.