Objectives The study aimed to assess the longitudinal changes in the ANB angle before and after adolescence, and determine Class I normative values for childhood and adolescent Caucasian patients based on cervical vertebral maturation stages (CVMS) and gender. Setting and sample population The sample included 71 (41 females and 30 males) untreated Caucasian subjects who took part in a growth study between 1959 and 1976. Materials and methods Lateral cephalometric radiographs were analysed at CVMS1 (childhood) and again at CVMS4-5 (adulthood). A paired sample t-test was used to analyse ANB angle differences between the two time points. Subjects who were skeletally and dentally Class I at adulthood (51 subjects) had their radiographs at CVMS1 (childhood) and CVMS2-3 (adolescence) used to establish Caucasian normative values for those stages. Data were also analysed for gender and skeletal classification differences. Results There was a statistically significant decrease in ANB value (2.3°) from CVMS1 to CVMS4-5 in the combined sample as well as the skeletal Class I and Class III groups (2.5° and 3.3° for Class I and Class III subjects, respectively). The reduction was smaller and not statistically significant in Class II individuals (1.5°). In Class I individuals, ANB values were 4.68° (SD:1.76°) at CVMS1, 2.86° (SD:1.18°) at CVMS2-3, and 2.13° (SD:0.99°) at CVMS4-5. No significant gender differences were found. Conclusions Statistically significant decreases in the ANB angle can be expected between childhood and adulthood in Class I and Class III patients but not Class II untreated subjects. Adult normative values should not be used for children.