The paper tries to answer two questions: the safety of the injection of gadolinium during breastfeeding; the value of a breast MRI in the nursing mother if breast cancer is suspected. Recent Anglo-Saxon publications are in favour of continued breastfeeding following the injection of gadolinium. In fact, only a minute quantity of contrast product passes into the mother’s milk, much less than the threshold recommended in paediatrics in the infant. However, a suspension of lactation for 24h after the injection of gadolinium chelate is still recommended in France. The literature is poor as regards the contribution of the MRI during lactation, although the data indicates that the MRI is contributory, in spite of the physiological changes in the breast during this period. In fact, all of the lesions have been visualised and correctly classified according to the BI-RADS classification by the ACR^{1http://www.acr.org/SecondaryMainMenuCategories/quality_ safety/BIRADSAtlas/BIRADSAtlasexcerptedtext/BIRADSMRIFi rstEdition.aspx xxxinvasion of the lymph glands.} . However, the semiology is specific and has to be known.