Contrast-enhanced magnetic resonance (MR) imaging is increasingly used as a complementary diagnostic modality in breast imaging. The sensitivity of MR imaging of the breast for malignancy has consistently been reported to be excellent. The specificity has been rather variable. Study methods and imaging techniques are not standardized and there is still a great deal of uncertainty about MR imaging's place in clinical practice. Nevertheless, radiologists should be familiar with the current technique and the varying MR appearance of breast tumors to improve the accuracy of this method. This paper reviews the techniques for breast MR imaging, the pathopysiologic basis of contrast enhancement in breast tumors, and the current knowledge about detection and differentiation of breast tumors. In addition, future directions for breast MR imaging are discussed.