Modic I vertebral end-plate signal changes detected by magnetic resonance imaging (MRI) are associated with chronic low back pain. Typically, Modic I signal changes in untreated patients switch to non–Modic I signal changes within 3 years, which reflect spontaneous healing. Recent findings suggest that Modic I signal changes may be related to local inflammatory changes, providing a rationale for treatment with intradiscal injections of antiinflammatory drugs. In the present report, we describe a 31-year-old man with 1-year history of chronic low back pain associated with vertebral end-plate Modic I signal changes, who received 1 intradiscal corticosteroid injection in L5–S1. Local treatment led to rapid pain relief and was associated with an accelerated switch from Modic I to Modic 0 signal changes, as seen on lumbar MRI at 1-month followup. This is the first report of an effective local treatment for both the symptoms and the structural changes of chronic low back pain that are associated with Modic I signal changes. Additionally, this case reinforces the hypothesis that local inflammation has a pathogenic role.