Abstract: The cells of periodontal epithelial rest are the only odontogenic epithelial cells presenting in periodontal ligament, but the exact function of periodontal epithelial rest is still unknown. It has been speculated that they have no physiological significance but only a pathological role in periodontal ligament. However, more recent investigations have shown that periodontal epithelial rest has been involved in the maintenance of the periodontal ligament space and cementum formation. The following discussion of embryological origins, morphological characteristics, protein expression and possible roles of periodontal epithelial rest was presented in this review.