In order to evaluate the normal eruption time of Korean permanent teeth, the uthor had examined the eruption phases of permanent central incisors in 714 malw and 581 female children aged from 4.5 to 9-year old and analysed. The eruption was divided into 3 phases; the tip of crown can be seen, the half of the crown can be easily seen, and full length of the crown can be seen. The obtained results were as follows : 1. It seemed that percentage of the erupting and erupted permanent central incisor in female by age was higher than that of male. 2. In general, percentage of the erupting and erupted lower central incisor by age was higher than that of upper first molar.