Congenitally missing teeth, or hypodontia, is one of the most common abnormalities of the human dentition and has a critical and often lifelong impact on the oral health of affected individuals. Here we review hypodontia and describe the patterns of inheritance it can display. A short review of tooth development and a primer in human genetics are presented. Approaches used to determine the underlying cause for various forms of hypodontia are discussed and information about genes discovered to date is reviewed. The role that the dental hygienists can play in facilitating the discovery of novel genes for hypodontia is illustrated.