In cases with maxillary lateral incisor missing, the problems were usually treated by the choice between space opening for prosthetic lateral incisor replacement and space closure with cuspid sub stitution for the alteral insicors. The decision of the choice could be perplexing in evaluation of the individual case. Therefore, various diagnostic criteria, such as occlusion, dental esthetics, canine position and inclination, tooth size relationship, maxillary lip length, and skeletal relation had to be evaluated. On the basis of this diagnostic information, the treatment planning could be established. A case was shown to illustrate the treatment of patient with congenitally maxillary lateral incisor missing.