Tumor size is an important independent indicator in patients with carcinoma of the breast. Repeated size measurements during primary systemic therapy produce detailed information about response that could be used to select the most effective treatment regimen and to estimate the patient’s prognosis. Measurement of tumor burden with ultrasonography and computed tomography is being used with increasing frequency to assess the effectiveness of cytotoxic anticancer drugs. Standardization of assessment and results reporting are important steps that aim at increasing the amount of usable therapeutic information at the physician’s disposal. The purpose of our study is to calculate the tumor volume by mammography after demagnification and compare the tumor volume measured from this method with ultrasonography volumes.