The purpose of this study was to analyze the breast growth variation trends and characteristics of Korean adolescent girls based on 3D body measurements. Subjects were 174 girls aged between 13 and 18. 3D body scanning data were collected and the data were measured by Geomagic Design X program. The total of 18 anthropometric measurements and 4 index items were analyzed. The main results of this study are as follows: 1) Overall, the breast growth of adolescent girls got out of children's body shapes at the age of 14 and the adult's body shapes appeared remarkably at the age of 18. Before the age of 15, the adolescent girls' breast enlarged. 2) The surface lengths of upper body, which means the breast volume, showed significant growth above B cup groups rather than under A cup groups. The demand of B cup size (32.2%) was higher than A cup size (25.9%). And 35.6% of subjects' brassiere band size was 70. 3) The thorax grew evenly in the circumference, depth and breadth. The thoracic development related to the breast volume as well as the whole upper body's development. These results reveal that it is necessary to develop adolescent girls' brassiere reflecting on adolescent girls' breast growth variation trends and characteristics by age, breast size and thoracic development.