Previous studies suggest that the pelvic morphology may be abnormal in adolescent idiopathic scoliosis. This study compares the sacropelvic morphology between normal adolescents and subjects with adolescent idiopathic scoliosis (AIS) in both sagittal and coronal planes. The sacropelvic morphology was assessed from the postero-anterior and lateral standing radiographs of 27 normal adolescents and 29 subjects with AIS presenting a major Cobb angle greater than 30°. Sacropelvic morphology was characterized by 19 parameters in the sagittal plane and 26 parameters in the coronal plane. There was no difference in sacropelvic morphology between the two groups in the sagittal plane. In the coronal plane, significant differences were found for right pelvic length, right iliac height, left and right pubic length, left obturator foramen width, bicristal distance, bituberal distance, biacetabular distance, pubic symphysis width, pelvic inlet, and subpubic angle. There was no significant pelvic asymmetry in AIS subjects. This is the first study that specifically evaluates the sagittal and coronal sacropelvic morphology in AIS. The results suggest that the coronal sacropelvic morphology is distorted in AIS. A longitudinal study is required in order to evaluate the influence of sacropelvic morphology in the progression of AIS.