Objective To investigate the clinical effects of pars repair by the pedicle screws,laminal hooks and auto iliac bone graft through the Wiltse approach via Quadrant channel for the treatment of the adolescent spodylolysis.Methods From November 2007 to April 2011,pars defects of 11 patients (10 males and 1 female) were repaired with pedicle screws,laminal hooks and auto iliac bone graft via Quadrant channel through the Wiltse approach.The mean age of 11 patients was 17.3 years (range 15-19).Mean course was 9.9 months (range 6-14 months).All patients have bilateral pars defect of L5.There was no poroma across the pars that have been proved by X-ray film and 3-D CT before the operation.There were 4 patients with Ⅰ grade spondylolisthesis.The degeneration of the intervertebral disc assessed by Pfirrmann grade of all patients was no more than Ⅰ grade.Visual analogue scale (VAS) and Oswestry disability index (ODI) were compared before and after operation.The fusion of pars defect was observed by X-ray film and 3-D CT.Results The mean operation time was 85.5±12.3 min (range 70-110 min); intraoperatve blood loss was 80-150 ml (mean 105 ± 19.4 ml).Two patients were lost in follow-up after operation and the others had been followed up for 12 to 24 months (mean 16 months).All patients had significant pain relief and function recovery after operation.Mean postoperative VAS score was 1.5± 1.0 compared with 4.5± 1.0 of preoperation (t=4.603,P=0.002).ODI was decreased from 49.3％± 14.2％ of preoperation to 12.0％±4.9％ of the last follow-up (t=7.344,P=0.000).With the Macnab grades,7 patients are excellent,2 patients are good.3-D CT showed that all pars defect were fused in the last follow-up.Conclusion Pars repair by the pedicle screws,laminal hooks and auto iliac bone graft through the Wiltse approach via Quadrant channel can protect the paravertebral muscle,relief patients from pain,and improve function.