Background: The use of preoperative breast MRI remains controversial despite being the most sensitive technique for the detection of breast malignancies. Purpose: To evaluate the benefit of preoperative breast MRI after performing the three conventional techniques (DM, US, DBT). To analyze the influence of breast density in the sensitivity of the different imaging techniques. Material and methods: Retrospective review of 280 histologically confirmed breast cancers in 192 women. We reviewed the medical records and evaluated the change of treatment induced by MRI. Also, we assessed the reports of DM and the combination of the different imaging techniques, and categorized them according to ACR density (a-d) and as negative (BI-RADS 1-3) or positive (BIRADS 4 or 5). The gold standard was the pathologic assessment of the surgical specimen. The sensitivity of the different techniques was compared using McNemar test. Results: Among these 192 women the use of MRI did not significantly increase the mastectomy rate (from 16.6% to 17.6%; p = 0.5). The addition of any technique demonstrated a higher sensitivity than DM alone. The sensitivity of DM alone was 52.5% while using all the techniques, including MRI, was 94.3% (p < 0.001). Regardless of breast density pattern, the addition of any technique significantly increased the sensitivity of DM (p < 0.001). Conclusions: The addition of MRI to the three conventional techniques increased the sensitivity but did not significantly modify the rate of mastectomies. Additional techniques increased the sensitivity of DM in both dense and non-dense breasts.