Dental anomalies of tooth number in development of the permanent dentition are quite common than the primary dentition, however, the combined occurrence of hypodontia and hyperdontia is a rare phenomenon, especially in the same dental arch. The purpose of this report is to describe a case of concomitant hypo-hyperdontia (CHH) in three patients (one girl and two boys) with missing mandibular central incisor and an erupted mandibular mesiodens. Three rare cases of mandibular CHH were observed during routine examination, where the two anomalies manifested in the anterior region of the mandible. Furthermore, these are the only cases exhibited taurodontism in association with mandibular CHH.