Aims. The aim of this study is to introduce and investigate the efficacy and feasibility of a new vertebral osteotomy technique, vertebral column decancellation (VCD), for rigid thoracolumbar kyphotic deformity (TLKD) secondary to ankylosing spondylitis (AS). . Patients and Methods. We took 39 patients from between January 2009 and January 2013 (26 male, 13 female, mean age 37.4 years, 28 to 54) with AS and a TLKD who underwent VCD (VCD group) and compared their outcome with 45 patients (31 male, 14 female, mean age 34.8 years, 23 to 47) with AS and TLKD, who underwent pedicle subtraction osteotomy (PSO group), according to the same selection criteria. The technique of VCD was performed at single vertebral level in the thoracolumbar region of AS patients according to classification of AS kyphotic deformity. Pre- and post-operative chin-brow vertical angle (CBVA), sagittal vertical axis (SVA) and sagittal Cobb angle in the thoracolumbar region were reviewed in the VCD and PSO groups. Intra- , post-operative and general complications were analysed in both group. Results. lf patients could lie on their backs and walk with horizontal vision and sagittal profile, radiographic parameters improved significantly post-operatively in both groups. No major acute complications such as death or complete paralysis occurred in either group. In the VCD group, five patients (12.8%) experienced complications such as severe CSF leak (n = 4), deep wound infection (n = 1) and in one patient a transient neurological deficit occurred. In the PSO group, eight patients (17.8%) suffered conditions such as severe CSF leak (n = 5), infections (n = 2) and sagittal translation at osteotomy site (n = 1). Scoliosis Research Society outcomes instrument (SRS-22) improved significantly in both groups. All patients achieved solid fusion at latest follow-up and no implant failures were noted in either group. Take home message: The VCD technique is a new, safe and effective strategy for correction of rigid TLKD in AS patients. The main advantage of the new correction mechanism is that it achieved a satisfactory correction by controlled anterior column opening and posterior column closing, avoiding the occurrence of sagittal translation. Cite this article: Bone Joint J 2016;98-B:672–8