Abstract: Objective: To evaluate the accuracy of mammography and color Doppler ultrasonography in the assessment of tumor size of breast cancer before operation.Methods: The tumor sizes in 70 patients with primary breast cancer before operation were measured using mammography and color Doppler ultrasonography,which was compared with the size of the tumor pathology after modified radical mastectomy.Results: The tumor size measured by mammography in premenopausal patients before operation was positive correlation with the postoperative breast cancer size measured by pathology(P<0.05),the tumor size measured by color Doppler ultrasonography in premenopausal patients before operation was not correlation with the postoperative breast cancer size measured by pathology(P>0.05).The tumor size measured by mammography and color Doppler ultrasonography in postmenopausal patients before operation were positive correlation with the postoperative breast cancer size measured by pathology(P<0.05 and P<0.01).The tumor sizes measured by mammography and color Doppler ultrasonography in patients without axillary lymph node metastasis before operation were positive correlation with the postoperative breast cancer size(P<0.01 and P<0.05).The tumor sizes measured by mammography and color Doppler ultrasonography in patients with axillary lymph node metastasis were not correlation with the postoperative breast cancer size(P>0.05).Excluding other clinical pathological factors,the tumor sizes measured by mammography and color Doppler ultrasonography before operation were positive correlation with the postoperative breast cancer size(P<0.01 and P<0.05).Conclusions: The accuracy of mammography in evaluating the tumor size of breast cancer is better than that of color Doppler ultrasonography.For some special structure and type breast,the accuracy of mammography in evaluating the tumor size still need to explore before operation.