This study was intended to investigate the effect of mesiodistal crown widths of the anterior teeth on the incisor relationship and to determine whether mcisor width ratio and anterior width tatio could be used to assess interarch tooth width harmony. From thr casts taken from 63 subjects, 26 of open bite, 18 of deep bite and 19 of normal over bite sith age of 17-20, mesiodistal crown widths of maxillary and mandibular 6 anterior teeth were measured with Boley gauge. On the basis of tooth measurements, anterior and incisor width ratio were calculated. The cephalograms were taken from same subjects to measure the degree of over bite and over jet and to compare the craniofacial bony structures between open bite, deep bite and normal over bite. Correlations among the anterior width ratio, incisor width ratio, over bite and over jet were calculated. The results were as follows. 1. There were no differences in mesiodistal widths of anterior teeht, incisor width ratio and anterior width ratio between open bite, deep bite and normal over bite. 2. The mcisor width ratio and anterior width ratio can bw useful in the assessment of tooth width harmony because the incisor width ratio and anterior width ratio were stable statistically and significantly correlated with each other. 3. Over bith and over jet were not correlated with incisor width ratio and anterior width ratio.