Background Data: One segmental fusion after hemivertebare resection is well used in children younger than 6 year old. But it is not reported in adolescent patients. One segmental fusion can be achieved through a temporary instrumentation which is shortened in two stage operations. Objective: to investigate the outcome of one-segmental instrumentation and fusion after posterior lumbar hemivertebrae resection in adolescent patients. Method: 10 consecutive congenital scoliosis patients with lumbar hemivertebrae were included between 2004 and 2011. Detailed physical and radiological examinations were performed on every patient. All hemivertebraes were single fully segmental. Posterior hemivertebrae resection was performed with cage or mesh for reconstruction. One segmental fusion with longer transpedicular instrumentation was performed at the first stage. The instrumentation was shortened to one segment at the second stage in half year. Full length radiograph of spine and dynamic radiograph of lumbar spine were performed at follow up. Result: There were7 male and 3 female. The mean age was 16.1 (range, 9.4 to 22.7). Cages were used in 3 cases and titanium meshes in 5 cases. At final follow-up, Cobb angle of the main curve became 12.6° from 51.1°, the kyphosis became -3.3° from 27.4°, the mobility of cephalic segment remained 3.2° and the caudal segment remained 4.6°. No neurological complication or pseudoarthrosis occurred till the final follow up. Conclusion: Its able to preserve two functional segments by a temporary longer instrumentation. Two stage operations are needed to shorten the instrumentation to one segment. At the first stage only one segmental fusion is performed. Good balance of spine was maintained in all cases at the final follow up. The additional surgery does not increase the rate of infectious and neurological complications.