To achieve an ideal facial appearance, considerations should be taken on the soft and hard tissue to make and evaluate a treatment plan. Especially, in case of adults with skeletal malocclusion, consideration should be taken to the thickness of the upper and lower lip as it showed various values as a result of the morphologic discrepancy with skeletal dentition and discordance with adjacent neuromuscular tissues. This study aimed at comparing the lip thickness around vermilion border of Class III subjects with normal subjects. Also it is to analyse the difference between two subjects. After taking the Computed Tomograph (CT) on the chosen adults with normal and Class III occlusion, the CT images were reconstructed into 3-dimensional images. Lip thickness was measured around central incisor, lateral incisor and canine area to the buccal surface of the each tooth. And then the lip thickness were compared and analysed corresponding to the tooth area in normal and Class III subjects. Also, a correlation analysis between 27 points in cephalogram, overjet, overbite and lip thickness was done. The results showed that the lip thickness of Class III subjects is different from that of normal subjects. The considerations should be taken on the lip thickness caused by skeletal discrepancy in diagnosing and making a treatment plan.