The differentiation between normal sequelae and complications of any surgical treatment of the lumbar spine is of the utmost importance. Clinical and radiological diagnosis is often difficult. Certainly the introduction of computed tomography (CT) and magnetic resonance imaging (MRI) has improved and refined the diagnostic possibilities, however not all problems have been resolved. For example, the frequent resort in vertebral surgery to metal implants which may limit or even prevent the interpretation of CT or MR images, should be kept in mind. The main types of surgical procedures involving the lumbar spine are briefly reviewed, focusing on CT and MRI appearance of normal sequelae of early or late complications and the recurrence of the lesion that necessitated the first procedure.