Three-dimensional tooth positions on maxillary dental casts of twenty-two male and female young Japanese having clear cusps. were measured by clinical measuring method. Average measuring errors between measuring persons were 0.12mm, 0.14mm, or 0.15mm, for antero-posterior. bucco-lingual. or supero-inferior measurement, respectively. First, setting the incisal point as the original point for measurement, three-dimensional positions of the middle points of the edges of lateral incisors, the tips of canines, the buccal/lingual and distal/menial cusp tips of the first and second premolars and the first and second molars, were measured antero posteriorly, buccal-lingually, and supero-inferiorly. The measured three-dimensional positions of each measured points on the left and right dental arrangements on the maxillary dental casts were averaged and the arithmetical means of their standard deviations were calculated. Average measuring errors between measuring persons were about 14th, 15thor 8thof the arithmetical means of the standard deviations of antero-posterior, buccal-lingual, or supero-inferior positions, respectively, indicating the deviation between measuring samples are prevailing over the measuring errors between measuring persons. Any statistically meaningful difference between left and right dental arrangements did not existed in antero-posterior and buccal-lingual positions, in contrast to that, some statistically meaningful difference between left and right dental arrangements existed in supero-inferior positions, indicating the existence of possible correlation between supero-inferior positions and lateral displacements of the mandible or chewing habit.