BACKGROUND The safety of cerebrospinal fluid (CSF) drainage in thoracic aortic surgery using extracorporeal circulation (ECC) with systemic heparinization has not been established. METHODS Four hundred thirty-two patients had descending thoracic or thoracoabdominal aortic repair between 1993 and 2002. One hundred sixty-two of those patients (age range, 67 +/- 13 years) had repairs performed with ECC, systemic anticoagulation, and lumbar CSF drainage. Repairs performed without CSF drainage, without ECC, or by stent graft (n = 53) were excluded. The CSF catheters were inserted at L3 to L5. Cerebrospinal fluid was drained to maintain pressures of 10 to 12 mm Hg. In the absence of neurologic deficit or coagulopathy, the catheters were capped at 24 hours and removed at 48 hours. Cerebrospinal fluid drainage was continued beyond 24 hours for delayed onset paraparesis. RESULTS Cerebrospinal fluid drains were used in 135 thoracoabdominal aortic aneurysms (extent I, n = 63; extent II, n = 25; extent III, n = 39; extent IV, n = 8) and 27 descending thoracic aortic repairs (aneurysm, n = 24; traumatic aortic injury, n = 2; aortic coarctation, n = 1). Partial left heart bypass was used in 132 patients, full cardiopulmonary bypass without deep hypothermic circulatory arrest in 5, and cardiopulmonary bypass with adjunctive deep hypothermic circulatory arrest in 25. Time between catheter insertion and anticoagulation was 153 +/- 60 minutes. Heparin achieved an average maximum activated clotting time of 528 +/- 192 seconds. Average ECC time was 114 +/- 77 minutes. Average deep hypothermic circulatory arrest time was 40 +/- 12 minutes. Mortality was 14.1% (23 of 162), and permanent paraplegia was 4.9% (8 of 162). No epidural or spinal hematoma was observed. Six (3.7%) patients had catheter-related complications (temporary abducens nerve palsy [n = 1]; retained catheter fragments [n = 2]; retained catheter fragment and meningitis [n = 1]; isolated meningitis [n = 1]; and spinal headache [n = 1]). CONCLUSIONS The CSF drainage in thoracic aortic surgery using ECC with full anticoagulation did not result in hemorrhagic complications. The permanent paraplegia rate in this complex patient population consisting of combined distal arch, thoracoabdominal aortic procedures were low, and lumbar CSF catheter-related complications had no permanent sequelae.