Laser scanning is a non-invasive method for three-dimensional assessment of facial morphology and symmetry. The aim of this study was to quantify facial symmetry in healthy adolescents and explore if there is any gender difference. Facial scans of 270 subjects, 123 males and 147 females (aged 15.3 ± 0.1 years, range 14.6-15.6), were randomly selected from the Avon Longitudinal Study of Parents and Children. Facial scans were processed and analysed using in-house developed subroutines for commercial software. The surface matching between the original face and its mirror image was measured for the whole face, upper, middle, and lower facial thirds. In addition, 3 angular and 14 linear parameters were measured. The percentage of symmetry of the whole face was significantly lower in males (53.49 ± 10.73 per cent) than in females (58.50 ± 10.27 per cent; P < 0.01). There was no statistically significant difference in the amount of symmetry among facial thirds within each gender (P > 0.05). Average values of linear parameters were less than 1 mm and did not differ significantly between genders (P > 0.05). One angular parameter showed slight lip line asymmetry in both genders. Faces of male 15-year-old adolescents were less symmetric than those of females, but the difference in the amount of symmetry, albeit statistically significant, may not be clinically relevant. Upper, middle, and lower thirds of the face did not differ in the amount of three-dimensional symmetry. Angular and linear parameters of facial symmetry did not show any gender difference.