The purpose of this study was to establish and describe normative cephalometric standards of the neurocranium (theca cranii and cranial base) for Norwegian males and females from 6 to 21 years of age using lateral cephalograms. The subjects included 35 males and 37 females from the Oslo University Growth Archive with lateral cephalograms taken every third year from 6 to 21 years of age. The total number of lateral cephalograms was 194 from males and 200 from females. All subjects were Caucasian, all had normal occlusion and no apparent facial disharmony, and none had undergone orthodontic therapy. Nineteen measurements and three indices of the neurocranium were analysed longitudinally. Comparisons between the various parameters in the neurocranium of males and females in each age group were performed using the Student's t-test. The size of the neurocranium of females was smaller than that of males throughout the observation period and the differences increased with age, particularly the diameter of the neurocranium (n-l), length of the neurocranium (n-opc), anterior cranial base length (n-s), and posterior cranial base length (s-ba). The cephalometric standards of the neurocranium established in this study can be used as a reference material in investigations of individuals with various craniofacial aberrations and syndromes.