A balanced sagittal balance is essential for maintaining the upright position with minimum muscular effort. Maintaining a balanced sagittal balance after lumbar fusion surgery is important for the outcome of surgery. Aim of work: The aim of this study is to compare different lumbar fusion surgeries on their effect on the sagittal balance and to assess the effect of the post-operative sagittal balance on the outcome of back pain. Patients and methods: Patients were divided into two groups, Interbody fusion group and posterolateral fusion group. The sagittal balance was calculated pre and post-operatively for both groups. The outcome of back pain and disability indices were calculated for both groups post-operatively. Results: There was statistically significant difference between the two groups as regarding the lumbar lordosis angle post-operatively. The mean lumbar lordosis angle was higher in the interbody fusion group than the posterolateral fusion group. The 3 months VAS score post-operative was significantly better in the interbody fusion group than in the posterolateral fusion group. Conclusion: The interbody fusion group was better than the posterolateral fusion group as regards maintaining sagittal balance post operatively. Maintaining the sagittal balance post-operatively was correlated with better outcome of back pain.