Methyl mercaptan is the metabolite of putative periodontal pathogen catalyzed by L-methionine-γ-lyase(METase). It plays an important role in cytoskeletal reorganization through increasing permeability of mucosa, cell migration through inhibiting synthesis and secretion of collagen and extracellular matrix, and in collagen degradation and alveolar bone resorption through immunological activities. Production of methyl mercaptan declines with inhibiting the enzyme activity. The objective of this article was to review the production of methyl mercaptan and the relationship of methyl mercaptan and periodontitis.