Matrix metalloproteinases (MMPs) are proteolytic enzymes involved in degradation of the extracellular matrix.In a previous study, MMP-13 was found to be expressed in pulp implying its involvement in the pathogenesis of dental caries. Two extracted teeth were used. A sound tooth and a tooth with wide range of dental caries were used. Two sections were obtained each from isolated crown and root. Immunofluorescence of the FITC of the MMP-13 in coronal and radicular dentin was analyzed by confocal microscopy. Immunofluorescence signals that were indicative of MMP-13 were observed in coronal dentin of sound teeth and in carious teeth with a wide range of caries. Marked immunofluorescent reaction was observed in the border line of caries infected and affected coronal dentin. MMP-13 expression was not detected in the root dentin. The expressions of MMP-13 in carious dentin imply the roles of MMP-13 in caries progression.