ABSTRACT Purpose This study aimed to compare skeletal age determination by using the ratio of third and fourth cervical vertebral dimensions (CVDs) versus the cervical vertebral maturation (CVM) method in an Iranian population. Materials and methods Lateral cephalometric radiographs of 240 patients were evaluated in this cross sectional study. The samples were classified into three groups (n = 80) of pre-peak of mandibular growth period (group 1), peak of mandibular growth period (group 2), and post-peak of mandibular growth period (group 3) according to the CVM stage. The dimensions of the third and fourth cervical vertebrae were measured. The anterior vertebral body height (AH) was divided by the anteroposterior vertebral body length (AP). The summation of the AH:AP ratio of C3 and C4 was calculated and reported as the SV. The correlation of SVs of 240 patients with their CVM stage was investigated. P-value less than 0.05 is statistically significant. Results SVs had a significant correlation with the CVM groups (P < 0.05). The area under the curve (AUC) was high for discrimination of group 1 from group 2 (AUC = 0.9776; 95% CI = 0.9448–0.9960), and also group 2 from group 3 (AUC = 0.9848; 95% CI = 0.9539–0.9984). The Youden index specified SVs of 1.29 and 1.61 as the best cut-off points for discriminating group 1 from group 2, and group 2 from group 3, respectively. Conclusions The two determined cut-off points could discriminate the groups with high sensitivity and specificity. Accordingly, we can use the CVD to determine the patients’ mandibular growth status.