This study was undertaken to establish the cephalometric standards of Hellman dental age Ⅲ A group of Korean on the roentgenocephalometry. The subjects consisted of 26 males and 29 females with the normal occlusion and acceptable profile. The following conclusions were obtained; 1) The tables of mean and standard deviation were made from the measurements of both male and female. 2) All linear measurements in male were greater than those in female. 3) Mandibular growth rate of female was greater than that of male. 4) Comparision of the children in Hellman dental age Ⅲ A with those in the late primary dentition indicated the tendency of facial vertical growth.