Assessment of the response of bone tumors to preoperative chemotherapy is of clinical importance. The authors determined the value of 3 imaging techniques (digital subtraction angiography, thallium scintigraphy, and dynamic magnetic resonance imaging) in guiding patient management by assessing the response of 17 bone sarcomas to preoperative chemotherapy compared with histologic evaluation of the resected specimens. Digital subtraction angiography showed a sensitivity of 87.5%, specificity of 57.1%, and accuracy of 73.3%. Thallium scintigraphy (sensitivity, 85.7%; specificity, 85.7%; accuracy, 85.7%) was superior to angiography in predicting tumor responses. The results of dynamic magnetic resonance imaging were analyzed on the basis of the value of slopes, which represents the percent increase in signal intensity per minute. The differences in slope before and after chemotherapy and the postchemotherapy slope values correlated with the histologic responses. The assessment by dynamic magnetic resonance imaging showed a sensitivity of 100%, specificity of 85.7%, and accuracy of 90.9%. Thallium scintigraphy and dynamic magnetic resonance imaging were considered noninvasive, reliable techniques that had about equal ability to assess the response of bone sarcomas to preoperative chemotherapy. Dynamic magnetic resonance imaging offers major advantages in the spatial resolution and can be more readily quantitated when compared with thallium scintigraphy.