Magnetic resonance imaging is the preferred exam for evaluating painful postoperative syndromes of the spine, allowing to differentiate between a recurrent hernia and postsurgical fibrosis, and evaluating arachnoiditis phenomena. The literature suggests a minimum waiting period of 8 weeks before MRI monitoring, for better clinico-radiological correlation after resorption of acute postoperative inflammatory phenomena. It also helps evaluate infectious complications, such as spondylitis.