The aim of this work is to prospectively evaluate the role of colour Doppler flow imaging with spectral analysis and dynamic gadolinium-enhanced magnetic resonance imaging in predicting the histopathologic response to chemotherapy in cases of lower extremity osteosarcoma. The study included 37 cases of classical osteosarcoma grade II and III, who underwent colour coded Doppler and dynamic enhanced MRI before and after neoadjuvant chemotherapy. Patients were grouped into poor and good responders according to the post operative histopathological percentage necrosis. It was concluded that colour Doppler ultrasound is good in predicting the poor responders after the second cycle of chemotherapy, when considering the wave form, and after the fourth cycle of chemotherapy when considering a good responder with increased QRI by 6.45% and decreased DFSs by 51.17%. The dynamic contrast enhanced MRI was also good in predicting the good responders when there was a reduction by 52.76% in the percentage slope value.