To determine extent of correction in spinal osteotomy for fixed sagittal plane deformity Radiographic retrospective cohort analysis using standardised standing whole spine radiographs. Level III evidence 24 patients (14 females/10 males, av. 53.6 yrs) with sagittal plane deformity due to either ankylosing spondylitis (4), idiopathic (12), congenital (1), tumour (2), infectious (1), or posttraumatic (4) aetiologies. Max. 4 yrs follow up Sagittal balance, lumbar lordosis correction, osteotomy angle, pelvic indices Chevron (3), pedicle subtraction (17), and vertebral column resection (4) osteotomies were performed with the majority at L3 (9) and L2 (8). The C7-S1 sagittal vertical axis demonstrated a preoperative decompensation averaging 12.0 cm (range -7 to 37) with 55% of patients achieving normal sagittal balance postoperatively. Lumbar lordosis increased from 28.9° (range -28 to 63) to 48.9° (range 12 to 69) (22.3° av. correction). L3 osteotomy angle was largest, average 31° (range, 16 to 47). There were 11 complications comprising; major (1) and minor (1) neurological, junctional kyphosis (3), metalwork problems (2), dural tear (2) and infection (2). Four patients required additional surgery at latest follow-up. Technical outcome was good 11(50%), fair 8(36%), poor 3(14%). Spinal osteotomy is a very effective technique to correct fixed sagittal imbalance and provide biomechanical stability. The high complication rate mandates a careful assessment of the risk/benefit ratio before undertaking what is a major reconstructive procedure. Most patients are satisfied, particularly when sagittal balance is achieved.