The purpose of this study was to investigate the characteristics of mesiodens among children in Korea. The study population consisted of 20 children whose ages ranged from 4 years to 26 years. The characteristics of mesiodens were obtained from radiographs and clinical examination results, and were confirmed by surgical intervention. Results showed that males were affected four times as frequently as female. Thirty-five percent of the patients had more than one supernumerary tooth. About 67% of the mesiodens were conical in shape and about 34% of the mesiodens were in the upward position. The age and sex distribution, number of mesiodens per patient, shape, direction, size, and effect on permanent upper incisors are also presented in this study.