The author has studied on the gonial angles in cephalometric roentgenograph and orthopantomograph. Lateral cephalometric roentgenograms and orthopantomograms were taken from 62 patients who were consisted of 32 boys and 30 girls with dentoalveolar Class I malocclusion. Gonial angles were measured on cephalograms and orthopantomograms respectively, and calculated the mean values and standard deviations and t test was performed on the relationship between the cephologram and orthopantomogram. Results were as followings; 1. Mean value of gonial angles was 126.47° ± 5.62 in cephalgram. In orthopantomograms the gonial angle was 125.23° ± 6.68 in left side and 126.47° ± 6.85 in the right side. 2. Result of t test showed no significant differences on the level of 1 percent.