A case of life-threatening complication resulting from a lumbar epidural block is presented. A 70-year-old woman with spinal stenosis developed cardiac and respiratory arrest 5 minutes after receiving a lumbar epidural block containing 80 mg of triamcinolone acetonide and 6mL of 1.5% lidocaine. The patient received cardiopulmonary resuscitation and recovered without any sequelae. It is suggested that this complication was caused by subdural or intravascular injection of local anesthetics. It might be preventable by injecting a test dose of local anesthetics before injecting a full dose of local anesthetics and by using fluoroscopy.