Background: Spondylolysthesis represents a particular and relatively frequent mechanism of intervertebral instability. It could cause low back pain due to forward or anterior displacement of one vertebra in relation the adjacent lower vertebra. There are many treatment interventions. However, there was no consensus on the ideal approach. Aim of the work:To assess the outcome of trans-pedicular screw fixation with posterior inter-body fusion in management of lumber and lumbosacral spondylolysthesis.Patients and Methods: This is a prospective study, included twenty patients who underwent surgical lumbar laminectomy and disc removal with lumbar pedicle screw fixation with inter body fusion for patients with Spondylolysthesis who failed conservative measures. Results:The mean preoperative visual analogue score (VAS) for pain was 7.75 ± 0.72 that decreased to 1.35 ± 0.59 at the end of postoperative sixth month, with statistically significant decrease. In addition, the majority of cases had no significant complications, although complication rate was 25%. Conclusion:Posterolateral fusion with pedicle Screws fixation minimizes dislocation, achieves adequate decompression, corrects the sagittal axis, and accomplishes fusion. We successfully achieved solid fusion with good mechanical alignment in majority of the patients.