Purpose: To assess the effect of patient positioning on the position of the kidneys and their consequent projection onto plain radiographs, thus ascertaining the need for special preoperative imaging. Patients and Methods: Fourteen patients were studied by obtaining fine (5-mm)-cut contrast-enhanced CT scans in the pyelogram phase in both the supine and prone position. The orientation of the kidneys relative to the midsagittal plane of the body and the orientation of the anterior and posterior calices relative to the axis of the kidney were measured from hardcopy images. Comparison was made between prone and supine positions for left and right kidneys separately, as well as overall. Results: The position of the patient had a small effect on the orientation of the kidneys, with the mean angle changing from 56.6°when supine to 61.6°when prone (p < 0.05). However, no significant change in caliceal orientation or the relative projection of the anterior and posterior calices occurred as a result. Conclusion: There is no need to carry out special preoperative imaging in the operative or prone position.