Computed tomography(CT) has become more widely available in recent years and is recognized as an important diagnostic tool for complex disease and condition of the orofacial structure in adults. In pediatric patients, especially in the mixed dentition period, the number of superimposing dental structures in the jaw bone is much greater than in the permanant dentition period. Therefore, in spite of radiation risk, computed tomography should sometimes be used in pediatric patients in order to obtain a precise and valid diagnosis. This case study presents clinical application of computed tomography on patients visiting department of pediatric dentistry in Seoul National University Dental Hospital. The results obtained through these cases were summarized as follow : 1. Localization of impacted teeth using CT allows for efficient treatment planning leading to reduced postoperative complications. 2. In orthodontic traction of impacted permanent teeth, utilization of CT made exact localization of window site and determination of prognosis possible. 3. Use of CT made possible definite diagnosis of lesions in the jaw that were only suspected on plain film radiographs. 4. Careful selection is necessary when applying CT on children due to increased radiation dose and high cost.