Abstract Genetically complex diseases like periodontitis have been extensively studied over the past decade. With the pooled knowledge about genetic polymorphisms that were claimed to play a role in the predisposition to and the progression of aggressive and chronic periodontitis, it is now possible to identify candidate genes that could act as potential risk or protective factors for the disease. Genetic researches in periodontitis were generally focused on 1) inflammatory cytokines, 2) cell surface receptors and 3) enzymes and related factors. Our reports have indicated the positive relationship between IgG Fc receptor (Fcγ R) IIIB, Fcγ RIIB, interleukin-1 receptor antagonist (IL-1RN), IgA Fc receptor (Fcα RI) gene polymorphisms and aggressive periodontitis in Japanese. Moreover, variations in the Fcγ RIIIA, Fcγ RIIA, tumor necrosis factor (TNF) receptor 2 and IL-6 gene correlated with the severity of chronic periodontitis. Periodontitis may be explained not only by the presence of specific bacteria and environmental factors, but also by the several relatively common polymorphisms with cumulative high-susceptibility profiles.