Although rare, major complications after spinal and epidural anesthesia do occur. The safety of spinal and epidural anesthesia has been well established. This is a report of an epidural hematoma in a patient with ankylosing spondylitis who received aspirin for thromboprophylaxis after total hip replacement that was unrelated to the combined spinal-epidural anesthetic. Most epidural hematomas are spontaneous and idiopathic.