The basic assumption in this work is that a scoliotic patient presents a rotation between the shoulders and the pelvis strictly connected with the torsion associated with the scoliotic deformity. In a scoliotic thoracic curve, the spinous processes rotate towards the curve concavity; in patients with a single right convex thoracic curve, the ribs and the whole chest should rotate in a clockwise direction while patients with a single left convex thoracic curve should present a counterclockwise rotation. The obtained results confirm such a basic assumption and allow to point out the various relationships between the trunk rotation and other, commonly used, spinal parameters.