Approximately 40 million students in the United States and a similar number in Europe carry school rucksacks. The average student carries a rucksack weighing almost one fourth of his or her body weight. This has led to more than 7,000 A&E referrals each year related to carrying school bags in the US. The purpose of this study was to investigate the effects of carrying a rucksack (on each shoulder or on both), on 3D spinal curvature in healthy young students. A convenience sample of 30 healthy young adults participated in this study. A Microscribe 3DX digitiser recorded the three dimensional coordinates of thirteen key anatomical landmarks along the spine in four different loading conditions; no rucksack (reference) carrying a rucksack (17% body weight) simultaneously on both shoulders and solely on the right or the left shoulder. The data obtained was analyzed using standard statistical methods. Carrying the load on both shoulders resulted in no difference in the frontal plane angle but significantly decreased the thoracic kyphosis in the sagittal plane. However, carrying the load on the right shoulder significantly increased the thoracic lateral curvature in the frontal plane and decreased the thoracic kyphosis in the sagittal plane. This study confirms that even carrying a 17% load causes significant changes in spinal alignment. It is essential that Health and Safety professionals promote the awareness and effects of diverse rucksack carriage modes and excessive rucksack weight to avoid the early onset of low back pain.