Refractory deformity in ankylosing spondylitis is caused by loss of normal lordotic curvature in lumbar spine. For the correction of deformity, monosegmental osteotomy, intracorporal decancellation and multisegmental osteotomy are used. Among them, multisegmental osteotomy is reported to be safe because of its small correction amount at each level. Since 1989, authors treated 5 cases of ankylosing spondylitis with severe kyphotic deformity by multisegmental osteotomy and transpedicular instrumentation. All were young males between 22 and 35 years of age. Preoperative kyphotic deformity was 80°, 105°, 72°, 35°, 55° (Av. 70°) and amount of correction was 55°, 105°, 72°, 20°, 40° (Av. 58°) respectively. Levels for osteotony were 4 to 8 segments and correction at a level was 5° to 13° (Av. 8.3°). Normal standing upright posture and vision for straight forward were obtained in all. Instrumentation was Zielke in three Cotrel-Dubousset in two. One case of Zielke instrumentation showed rod failure. However, all showed solid bony union without any loss of correction or pseudoarthrosis. From the above experience, multisegmental osteotomy for the treatment of kyphotic deformity in ankylosing spondylitis was believed to be a safe and effective method of treatment.