Periodontitis is deined as an inlammatory disease of supporting tissues of teeth characterized by progressive destruction of the periodontal ligament and alveolar bone. Periodontal manifestations of these genetic disorders or syndromes, such as familial and cyclic neutropenias, granulomatous disease, agranulocytosis, Langerhans' cell disease, glycogen storage disease, hypophosphatasia, leucocyte adhesion deiciency, and Papillon-Lefèvre, Chédiak-Higashi, Cohen, Ehlers-Danlos, Marfan, Down, Haim-Munk, and Kindlers syndromes, imitate some types of periodontal diseases. Most of these syndromes have autosomal-recessive characterization and can be seen commonly in consanguineous marriages. Therefore, consanguineous marriages have generally been accepted as having important detrimental efects on ofspring. There is a lot of genetic research about consanguineous marriage and its detrimental efects on ofspring. Although consanguineous marriages are common in the world, the relationship with oral and periodontal diseases has not been thoroughly investigated. We do not have enough of an understanding of the efects of consanguineous marriage on oral and periodontal diseases. In this chapter, previous studies in the literature related to this subject will be investigated and evaluated, and then this research will be related to oral and periodontal diseases. Therefore, this chapter will guide further research. The aim of this chapter is to show the relation between consanguineous marriages and oral-periodontal diseases.