The purpose of this study was to compare computed tomography (CT)/myelography and CT/diskography images, in a given patient, as a method of distinguishing postoperative fibrosis from recurrent herniated disk material. The study population consisted of 20 patients who had undergone lumbar diskectomy and subsequently developed recurrent radicular pain. All patients underwent CT/myelography and CT/diskography, each procedure performed within 72 h of the other. Comparison of transaxial images from CT/myelography and CT/diskography at a given disk space level yielded the following results: in 12 patients the extradural mass seen via CT/myelography corresponded entirely to the contrast-filled disk fragment seen via CT/diskography (recurrent herniated disk); in three patients the extradural mass seen via CT/myelography was larger than the disk fragment seen via CT/diskography (recurrent herniated disk and fibrosis); and in five patients CT/diskography images appeared normal, but CT/myelography showed an extradural mass (fibrosis). Fifteen patients underwent surgical reexploration with the following results: in three of three patients, the suspicion of recurrent herniated disk and fibrosis by radiologic evaluation was confirmed by surgical reexploration; in nine of 12 patients, solely recurrent herniated disk shown by radiologic criteria was similarly confirmed. The remaining five patients presumed to have fibrosis by radiologic criteria were treated nonoperatively.