Objective: To evaluate and compare sensitivity and specificity of ANB, Wits, APDI and AF-BF to diagnose sagittal skeletal malocclusions, in children between 6 to 12 years old, using ROC curves, a widely accepted method for the analysis and evaluation of diagnostic tests. Material and Methods: A descriptive-comparative study of diagnostic tests was conducted. From a population of 3,000 children, a non-probabilistic sample of 209 was selected. The clinical classification of the patients as class I, II or III, made by a group of experts based on the visual inspection of models and photographs, was chosen as the gold standard. After calibration (ICC>0.94) the variables were measured in cephalograms. Eight ROC curves were plotted (I vs II, and I vs III for each one of the variables). The area under the curve was measured and compared (Ji-square test). Cut points were established. Results: To discriminate Class I from II, ANB showed the largest area under the curve (AUC) (0.876) and the cut point (best sensitivity and specificity) was at 5.75°. To discriminate class I from III, Wits showed the largest AUC (0.874) with a cut point of -3.25 mm. There were no statistical differences between the AUC for the four variables (p=0.48 y p=0.38 for class I-II and I-III). Conclusion: ANB and Wits performed better for the diagnosis of class II and III, respectively. Cut points in children were different from those reported in adults.