The contribution of breast MR imaging for second intention after a complete assessment (mammography, ultra-sound, and possibly histological) of breast pathology is not any more to show. Its limits are due primarily to its great sensitivity responsible for false positive (20 to 40 %) and to the difficulty in carrying out biopsies under guidance IRM of the lesions not found in second intention by the mammography and ultrasound (50 to 75 %). Its use reasoned by respecting the indications recognized as useful and validated for the clinical plan is an imperative condition to avoid noxious assumptions of responsibility of the patients.