Breast cancer diagnosis and treatment are important health care issues in the Industrialized World. About 180,000 new breast cancers are discovered annually in the United States. Because this cancer often occurs in premenopausal women, breast cancer is a leading cause of potential life years lost. Breast magnetic resonance imaging (MRI) is capable of producing detailed information concerning the extent and character of breast lesions. The technique and alternatives for generating high-resolution breast MR images are reviewed. Characteristic features of a pulse sequence for breast imaging includes heavy T1 weighting and magnetization transfer weighting for more effective gadolinium contrast, fat suppression, and rapid acquisition time. MRI is best employed for breast cancer diagnosis as a supplement to conventional breast imaging. Diagnostic groups particularly well suited to breast MRI include women with radiographically dense breasts, silicone augmentation, and postoperative scar. The capacity of breast MRI to show disease extent is employed to plan and localize for breast-conservation therapy. Tumor size and multiple tumors can be characterized for more-effective surgical management. Ductal carcinoma in situ can be imaged and staged for tailored therapy. MRI-directed biopsy and localization can be used to optimize lumpectomy surgery and reduce the potential for histologically positive margins. MRI can define the effectiveness of radiation therapy and chemotherapy to provide improved information on nonsurgical treatment of breast cancer. The clinical implementation of breast MRI in the future depends on the careful coordination of quality MRI images and interpretations with skillful therapeutic management.