It is often difficult to predict postoperative radiographic curve magnitude and balance parameters while performing intraoperative correction during scoliosis surgery. We asked whether there was a radiographic correlation between intraoperative long-cassette scoliosis film and postoperative standing radiographs of adolescent idiopathic scoliosis with pedicle screw instrumentation. We retrospectively reviewed 44 patients with adolescent idiopathic scoliosis who underwent posterior instrumentation with pedicle screws. We made preoperative, intraoperative (after instrumentation and correction), and standing postoperative radiographic measurements (eg, curve magnitudes, coronal and sagittal balance, disc angles) and compared those for the intra- and postoperative radiographs. The intraoperative long-cassette scoliosis film correlated with the immediate postoperative standing film for all curve correction and balance parameters. The routine use of a long-cassette intraoperative scoliosis film provides the surgeon with a valuable tool to guide intraoperative decision-making and foreshadows the correction and balance obtained on the immediate postoperative film. Level of Evidence: Level IV, retrospective study. See Guidelines for Authors for a complete description of levels of evidence.