The surgical repair of thoracoabdominal aortic aneurysms (TAAA) remains challenging. The prevention of spinal cord ischemic complications requires a multidisciplinary approach. The protective effect of left heart bypass (LHB), particularly regarding spinal cord ischemia, during the repair of extensive TAAA is evaluated here. Data from 1,250 consecutive patients who underwent the repair of extent I or extent II TAAA over a 16-year period was prospectively entered into a database. LHB was used in 666 (53.3%) patients. This group was retrospectively compared with 584 (46.7%) patients who had undergone surgery without the use of LHB. A total of 1,173 (93.8%) patients were 30-day survivors. Paraplegia or paraparesis developed postoperatively in 68 (5.5%) patients. In patients with extent I TAAA, paraplegia and paraparesis rates in the LHB cohort (9 of 290, 3.1%) and those without LHB (13 of 313, 4.2%) were statistically similar (P=0.866). The latter was observed despite the fact that longer clamp times were used in the LHB group. In patients with extent II TAAA, the LHB group had a statistically significant lower incidence of paraplegia or paraparesis (17 of 375, 4.5%) compared with the non-LHB group (29 of 259, 11.2%; P=0.019). In our experience, we identified LHB as protective for reducing the risk of postoperative paraplegia and paraparesis in patients who underwent the repair of extent I and extent II TAAA, the latter statistically significant.