To determine the role of abdominal computed tomography (CT) that had been performed for other reasons, in the evaluation of degenerative changes of the sacroiliac joints, the authors performed a retrospective review of the sacroiliac joints of 100 patients, all of whom had an abdominal CT scan and a plain abdominal and/or pelvic roentgenogram in their files. The results indicate that, when available in the patient's record, abdominal CT scans provide substantial additional information in the evaluation of degenerative changes of the sacroiliac joints at no extra cost. The authors' results also suggest that after the age of 55, the patient's age does not seem to influence the extent of sacroiliac joint narrowing, which does appear to be affected by the presence of coexisting diffuse idiopathic skeletal hyperostosis.