A study of a sample of 81 Korean adolescents was taken to determine the degree of correlation between mandibular anterior teeth size and the size of the canines and premolars. The correlation between the total mesiodistal width of the mandibular permanent incisors and that of maxillary or mandibular canine and first and second premolars ,was found to be 0.53 and 0.58, respectively. Further, regression constants were determined in an attempt to estimate the buccal segments from the mandibular incisors.