Caudal, lumbar, and cervical epidural steroid injections (ESI) have been used for a number of years. A suspension of methylprednisolone acetate or triamcinolone diacetate is injected with a diluent of normal saline or local anesthetic. Steroids are used to decrease nerve root inflammation and suppress neuronal discharge. Response to lumbar ESI has been correlated with herniated disk, nerve root irrigation, and recent onset of symptoms. Failure to respond has been associated with prolonged duration of pain, unemployment due to pain, nonradicular diagnosis, and smoking. The few well-performed studies of ESI have yielded conflicting results. For cervical ESI, radicular pain predicts a better response; a radiologic diagnosis of herniated disk or a normal scan predicts a poorer outcome. ESI-related complications occur infrequently and are generally benign. However, adrenal suppression occurs for 1 month after injection. Preventive efforts are indicated for the rare but serious sequelae of epidural hematoma or abscess formation.