The authors report the case of an extradural spinal cyst in a patient whose only complaint was lumbar pain and review the literature. Among the 186 cases found, only 21 presented with isolated back pain. Indeed, neurologic signs such as paresthesias and radicular pain are most frequently encountered. Standard radiographic X-rays suggest the diagnosis by demonstrating widening of the interpedicular distance on the anteroposterior view, and bone erosion or scalloping of the posterior surface of the vertebral bodies on lateral view. Myelography most often confirms the diagnosis with opacification of the cyst. However, the least invasive and most accurate examination is undoubtedly magnetic resonance imaging, which demonstrates the cyst and its location even if the communicating orifice is obstructed. These cysts are very probably of congenital origin and are caused by a herniation of the arachnoid through an aplastic area of the dura mater. Treatment is always surgical with, if possible, ligature at the base and cyst removal. Following surgery, the pain disappears and the neurologic signs very often regress.