STUDY DESIGN: A retrospective study of neurologic complication with peridural hematoma was performed in the cases of operation for the lumbar degenerative disease. OBJECTIVES: To prove the risk factors of the postoperative neurologic complication, and the relationship between the symptom onset, the evacuation time and the neurologic recovery. SUMMARY OF LITERATURE REVIEW: There are rarely proven risk factors related with perioperative hematologic change, and the proper evacuation time is in controversy. MATERIALS AND METHODS: In 1280 operations from 1995 to 1999, there were 20 cases of neurologic complication with peridural hematoma. We considered age, sex, operative method, number of operation segment, hematologic variables, operation time and estimated blood loss as possible risk factors. The mean follow up was 19 months. The recovery was evaluated by comparison with the preoperative motor power, and we considered the time relationship of surgical outcome with the symptom onset and the time to hematoma evacuation. RESULTS: Neurologic sequelae occurred in 1.6%. The only detected risk factor was the increased number of operation segment more than 4. There were two types of onset, less than 12 hours and beyond 30 hours. Neurologic sequelae were completely recovered in 14 cases, 75% in acute onset and 83% in the delayed (p>0.05). According to the evacuation time, rapid hematoma evacuation within four hours made better recovery. CONCLUSIONS: We thought that the best way to prevent the neurologic sequelae is close observation and rapid evacuation if peridural hematoma is suspected.