Arch structure and arch function play an important role in maintaining balance, bearing body weight, and absorbing ground reaction forces. However, arch structure and arch function are known to vary extensively and may be affected by factors such as gender, age, and obesity. Therefore, the purpose of this study was to examine the influence of gender, age, and body mass index (BMI) on arch height and arch stiffness. A total of 173 participants (aged 57.60 ± 11.19 years, mean BMI 25.12 ± 3.93 kg/m) participated in this cross-sectional study. A 3-dimensional laser scanner was used to measure foot structure information in each subject, from which arch height and arch stiffness were calculated. The results showed that women had low-arched feet compared with men (p = .001), and no arch stiffness difference was found. Older individuals tended to have a stiffer arch than middle-aged and younger individuals (p < .05), and no arch height difference was found. BMI had an impact on arch height (p < .05) but not arch stiffness. Finally, a weak positive relationship existed between arch height and arch stiffness (r = 0.32, p < .01). The findings suggest that gender, age, and obesity have a certain impact on arch structure and arch stiffness. Figuring out the relationship between these factors and arch structure may be helpful in understanding the bases of foot deformity and foot dysfunction.Copyright © 2019 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.