Abstract Background data: Posterior cervical laminectomy and lateral mass screw-rod fusion techniques were classically recommended in flexible sagittal cervical alignment relying on indirect decompression via posterior cord shift. Purpose: To investigate the efficacy of Posterior cervical laminectomy with lateral mass screw-rod fixation for the treatment of Multisegmental Cervical Spondylotic Myelopathy with flexible sagittal cervical alignment. Study Design: Prospective clinical cohort study. Patients and Methods: Thirty eight patients with clinically symptomatic M-CSM with instability and/or flexible kyphosis were admitted to our Zagazig university hospitals for posterior cervical laminectomy and lateral mass screw-rod fusion (long-segment instrumented fusion ≥3 segments) and completed the 24 months follow-up period; between April 2014 and June 2018 and the last follow-up visit took place in October 2020. Patients were categorized into lordotic, straight, and kyphotic groups according to the shape of the cervical spine curve on neutral lateral x-ray view. Results: A total of 266 lateral mass screws were inserted in 134 levels in 38 patients (3 levels in 20 patients, 4 levels in 16 patients and 5 levels in 2 patients), all the patients had good fusion and the cervical spine was stable, based on the absence of hardware failure or subsidence. All of the 38 patients (100%) gained more lordosis with a variable degree according to the preoperative cervical sagittal alignment. The mean percentage of neck pain improvement according to Visual Analogue Scale (VAS) for the lordotic group was 69.1%, for the straight group was 43.8%, and for the kyphotic group was 15.8%.The mean percentage of neurological functions improvement(JOA score) for the lordotic group was 83.17%, for the straight group was 43%, and for the kyphotic group was17%.The mean percentage of disability improvement (NDI score) for the lordotic group was 47.66%, for the straight group was 24.5% , and for the kyphotic group was 16.66%. Conclusion: Decompressive cervical spine laminectomy and Lateral mass screw stabilization is an effective technique for treatment of Multisegmental Cervical Spondylotic Myelopathy with flexible sagittal cervical alignment.