Background: Magnetic resonance imaging of the breast is becoming a useful adjunct to mammography and sonography for the detection of breast lesions. However, it is not yet accepted as a routine examination for all breast cancer patients due to the lack of data regarding whether breast magnetic resonance imaging impacts recurrence or survival. This trial examines the use of magnetic resonance imaging for detection of additional lesions in patients with dense breasts and its effect on surgical treatment.Methods: Between November 2011 and November 2012, 51 patients with a confirmed diagnosis of breast cancer and dense breasts underwent bilateral breast magnetic resonance imaging. Cases were reviewed to determine if the breast magnetic resonance imaging detected additional masses, changed the preoperative clinical staging, the operation plan, or prompted additional testing.Results:Magnetic resonance imaging detected 37 additional masses in 19 patients that were not detected by mammography. Cancer occult to mammography was detected by magnetic resonance imaging in one woman. Breast magnetic resonance imaging upstaged the cancer in 7 (13.72%) out of 51 patients. Magnetic resonance imaging impacted surgical treatment in 4(7.84%) out of 51 patients.Conclusions: Magnetic resonance imaging is effective in the identification of additional masses in dense breasts that are not visualized on mammography. Of the 51 patients, 4 (7.84%) who underwent magnetic resonance imaging altered their surgical management due to the magnetic resonance imaging findings. Further studies should be undertaken to show that breast magnetic resonance imaging can change local recurrence and survival.