En bloc resection of primary sacral tumors has a demonstrated survival benefit. Total and high sacral amputations are traditionally performed by using a staged anterior and subsequent posterior approach. However, we have found that en bloc resection and biomechanical reconstruction of the spinal column is possible from a posterior-only approach in many cases. To assess our series of posterior-only sacrectomies, emphasizing postoperative complications and overall surgical and oncologic outcome. Sixty-nine consecutive patients underwent sacral resections for tumor at our institution between 2004 and 2009. Medical records of all patients were reviewed, and patients were excluded if they had an intentional intralesional resection, hemipelvectomy, or a previous operation. The records of the resulting 36 consecutive patients who underwent primary posterior-only en bloc sacral resections were retrospectively reviewed. Of the posterior-only patients, all underwent midline posterior approaches for en bloc sacral resection. Sacral amputation was defined by the by sacral root preservation: total (2 cases), high (8 cases), middle (9 cases), low (12 cases), and distal (5 cases). Chordoma was the most common tumor type (30 cases), and surgical margins were marginal in 34 cases and contaminated in 2. Overall, there were 13 complications, including 9 wound infections/revisions. The extent of sacrectomy, and thus the extent of roots sacrificed, correlated with functional outcome. It may be possible to perform a posterior-only approach to en bloc sacral resections/reconstructions in patients with tumors that do not extend beyond the lumbosacral junction or invade the bowel requiring bowel resection and diversion.