Introduction: Apical periodontitis represents a local immune response directed against the progression of microorganisms from the dental pulp to the apical foramen and periapical tissues, which results in bone and dental resorption. The aim of this review is to describe the expression of this group of proteases in apical periodontitis and its modulation during the periapical healing phase following root canal treatment. Literature review: The pathogenesis of apical periodontitis involves degradation of several extracellular matrix components. Matrix metalloproteinases (MMPs) are expressed in response to specific stimuli by resident cells of connective tissue during tissue remodeling and by inflammatory cells that arrive into the surrounding tissues during inflammatory events. MMPs have been reported in apical periodontitis, either experimentally induced or obtained from humans and there is evidence that these enzymes show diff erent expression patterns in granulomas and periapical cysts. Root canal therapy is important for the reduction of periapical inflammation as well as the synthesis of MMPs, especially when using a calcium hydroxide-based dressing. Conclusion: Apical periodontitis show high expression of matrix metalloproteinases and root canal treatment results in less expression of MMPs when compared to untreated apical periodontitis.