Successful management of patients with persistent or recurring pain after lumbar disc surgery requires comprehensive evaluation to accurately localize the anatomic sources of pain. The results of reoperation for recurrent disc herniation are uniformly good, whereas those of reoperation for scar tissue are poor. There have been few studies comparing the ability of enhanced MRI and CT/discography to distinguish between scar tissue and recurrent disc herniation. We evaluated 23 patients with recurring pain after lumbar disc surgery. Two neurosurgeons independently reviewed CT/discography and MRI of each patient before and after gadolinium enhancement. To determine the accuracy, sensitivity, and specificity of each test, responses were compared with surgical findings and CT/discography was found to be more sensitive and specific in distinguishing between scar and recurrent disc herniation. Characteristics associated with recurrent disc herniation include nonenhanced or rim-enhanced abnormality surrounding a low signal on enhanced MRI. and extension of contrast into the epidural space on CT/discography. For determining the need to repeat open disc surgery, combined MRI and CT/discography is more accurate and sensitive than either test alone.