Periodontal disease is a complex, multifactorial disease and the predisposition to its occurrence is genetically determined. A multitude of research projects on genotyping of patients and controls in search of putative genetic risk factors has been performed. The disease however is also dependent on the presence of environmental and lifestyle factors, and their interaction with the various genes. Many candidate genes have been proposed and studied in relation to periodontitis. Most of the studied candidate genes code for proteins that play a role in the innate immune system. Both, IL-1 and TNF-a play an important role in the development of periodontal disease. Till today there is no strong evidence for target genes and gene polymorphisms that play a key role in the susceptibility to and severity of periodontal disease.