Background: Spastic diplegic children suffer from spasticity, muscle tightness and limitation of range of motion impeding their functional abilities and gait. purpose: To evaluate the immediate effect of low frequency whole-body vibration on spasticity, popliteal angle, and gait kinematics in spastic diplegic children. Methods: Study was carried out on forty spastic diplegic children their age ranged from 4 to 6 years old they were selected from the outpatient clinic of the Faculty of Physical Therapy Cairo University, they had level 1 and II according to the gross motor function classification system and had grade of 1 and 1+ spasticity according to modified Ashwarth scale, Hoffman reflex (H/M) was used to assess spasticity,2- in-1 Digital Angle Ruler used to assess the popliteal angle range and Tekscan Software was utilized to evaluate gait kinematics. Results: there is significant decreases in spasticity and popliteal angle immediately after application of whole-body vibration associated with significant improvement of kinematics gait parameters (P< 0.001). Conclusion: Low frequency whole body vibration is an effective modality for spastic cerebral palsied children it reduced spasticity and improves range of motion and kinematic gait parameters.