The amount of orthodontic movement is limited by the borders of the alveolar bone. Objectives: The study aims are to establish pre-treatment cephalometric dimensions for the anterior alveolar widths in a hospital-based adult Chinese sample; and to determine differences in anterior alveolar width with consideration of the treatment planning decision for surgery or non-surgery. Methods: Pre-treatment lateral cephalograms of 277 adult Chinese pre-orthodontic patients (M=117, F=160) were included in the study. The cephalograms were manually traced and measured using a 3M Orthodontic protractor to the nearest 0.5° and the Mitutoyo Digimatic Digital Caliper to the nearest 0.01mm. From a set of 11 skeletal landmarks and 4 skeletal planes, 5 linear measurements were made. The widths of the upper and lower anterior alveolus are expressed as the U-ratio and L-ratio, respectively, with respect to ANS-PNS. A thin alveolus is defined as being equal or less than one standard deviation below the mean for the subject's mandibular divergence group. Descriptive statistics was used to analyze alveolar widths. Analysis of Covariance was used to test for between-subjects effect and pairwise comparisons. Significance was set at 5%. Results: For average mandibular divergence, the mean U-ratio is 0.3145 ± 0.0543 and the mean L-ratio is 0.2052 ± 0.0377. For mandibular hyper-divergence, the mean U-ratio is 0.3055 ± 0.0587 and the mean L-ratio is 0.1856 ± 0.0434. For mandibular hypo-divergence, the mean U-ratio is 0.3272 ± 0.0562 and the mean L-ratio is 0.2149 ± 0.0400. The mean L-ratio of the non-surgical group is significantly larger than the surgical group (p=0.032). Conclusion: The anterior alveolar dimensions, as expressed by ratios, suggest that subjects indicated for surgical correction of the malocclusion have a smaller mean L-ratio compared to the non-surgical group.