We analyzed height, weight, and body-mass index of 54,030 male and 38,102 female army recruits who underwent a complete routine health assessment at the age of 17 years. Totally, 6,711 males and 4,864 females were diagnosed as having idiopathic scoliosis and were categorized according to 3 grades of severity. There was a difference in prevalence in both sexes with parental origin from Iraq and western Europe. Females as compared with the males were at increased risk of developing the more severe grades of scoliosis. Young scoliotic adults were taller, lighter, and thinner than the nonscoliotic controls. These differences in height, weight, and body-mass index correlated with the severity of the scoliosis. We suggest that genetic factors and growth pattern are of major importance for the prevalence of scoliosis.