Introduction: Spondylolisthesis refers to the forward displacement of one vertebra relative to another. Objectives: To compare between unilateral and bilateral transpedicular screw fixation in grade I-II short segment lumbar spondylolisthesis as regarding clinical and radiological outcome in the two groups. Methods: 100 Patients were divided into two groups according to surgical treatment: Group A (50 patients had unilateral transpedicular fixation). Group B (50 patients had bilateral fixation). Results: We found that bilateral group has nonsignificant better outcome in improvement rate (P>0.05) than unilateral group , significantly more hospital stay (P< 0.05) and more blood loss. The unilateral group had significant more decrease in adjacent motion segment abnormalities than the bilateral group (P< 0.05) but less fusion rate. Conclusion: Unilateral fixation offers less rigid construct than bilateral one with advantage of less adjacent motion segment abnormalities and disadvantage of less fusion rates