Background. Idiopathic scoliosis is a three-dimensional deformity of the spine and the trunk. The principle clinical method of estimation of the rotational deformity in the transversal plane of the body is the measurement of the angle of trunk rotation with a scoliometer. The aim of the study was to investigate the relationship between the angle of trunk rotation and the two radiological parameters: the Perdriolle angle of axial rotation and the Cobb angle of spinal curvature. Material and Methods. 50 children with single or double scoliosis (total of 65 curves) were examined clinically and radiologically. For each patient the angle of trunk rotation was measured with the Bunnell scoliometer, the Cobb angle and the Perdriolle angle were calculated at the a-p standing radiograph. Results. Strong positive linear correlation was found among the three parameters in thoracic curves. The correlation was less important in lumbar curves. Thoracic curves revealed superior values of the angle of trunk rotation and inferior values of the angle of Perdriolle than the lumbar curves matched for Cobb angle. Conclusions. Clinical measurement of the angle of trunk rotation with the use of a scoliometer can predict the value of the angle of the curve in thoracic scoliosis. This might replace a certain amount of radiological examination and reduce the patients' irradiation.