The response of the tumor to treatment protocol is defined by the degree of tumor necrosis. We tried to study the reliability of 99mTc (V)DMSA for assessment of response to chemotherapy after the first and 3-4 cycles of preoperative chemotherapy. Moreover detection of recurrent or residual viable tumor tissue using 99mTc (V) DMSA in comparison to 99mTc-MIBI. Our study revealed that: Scanning with 99mTc- (V)DMSA may give an early idea about the response to chemotherapy following the first cycle being not affected by MDR phenomenon as in 99mTc-MIBI. 99mTc(V)DMSA scanning has higher sensitivity in detection of recurrent bone tumors whereas 99mTc-MIBI has higher specificity. So it is better to combine both radiopharmaceuticals to get the advantage of both high sensitivity and specificity.