The investigators studied the height of adolescents in the age range of 12 to 18 years from 2 schools in Bangkok. Questionnaires asking their rates of organised exercise per week, of milk intake per day and their parental heights were given to a total of 545 male and 615 female students. The completed questionnaires were analyzed. We could categorize these subjects into 3 groups according to their heights which were Group I (height > 97th%-ile), Group II (height between 50-97th%-ile) and Group III (height < 50th%-ile). Those in Group I had parents, whose height was significantly greater than those of the other groups. There was no difference in organized exercise among the 3 groups. Milk intake of female adolescents from Group I was significantly more than the other groups. It is concluded that parents' height in both males and females and milk intake in females contribute to a greater adolescent height.