PURPOSE: This study aimed to quantify the effects of whole body vibration (WBV) stimulation training on the muscle thickness and gross motor function in children with spastic cerebral palsy. METHODS: Twenty children diagnosed with spastic cerebral palsy were assigned randomly to the Whole Body Vibration (WBV) group (n=10) and control group (n=10). The WBV group received vibration therapy including five different therapy, and the control group received only five general physiotherapy sessions. After 10 weeks of intervention, the muscle thickness was measured using ultrasound, and the Gross Motor Function D and E items were evaluated. RESULTS: After the intervention, both groups showed a significant increase in muscle thickness and gross motor function (p<.05). The WBV group showed a significant increase in the quadriceps femoris and tibialis anterior muscles compared to the control group, whereas no significant increase in the gastrocnemius muscle was observed (p<.05). The WBV group showed significant improvement in the Gross Motor Function D and E scores compared to the control group (p<.05). CONCLUSION: WBV training may be a useful way of improving the lower extremity muscle strength in children with spastic cerebral palsy, which may help improve the gross motor function.