Spontaneous herniation of the spinal cord is a rare disease entity in which spinal cord substance is herniated through a previously uninjured and/or untouched dura. It is a cause of myelopathy that is treatable but difficult to diagnose. We report the CT and MR findings of a case of spontaneous thoracic spinal cord herniation manifesting as ventrolateral protrusion of thoracic spinal cord through a dural defect.