The authors report nine personal cases in a review of the literature concerning cancers of the breast associated with pregnancy and lactation (until a year post-partum). The diagnosis of the illness is reported to be difficult in pregnant women and it is necessary to use fully all the diagnostic procedures available and in particular cytology and histology. Surgery is urgent. It is classical practice to carry out a mastectomy with axillary clearance. Nevertheless more conservative treatments are now being suggested. The principal problem of therapy is linked to the effects of adjuvant therapy on the fetus be they radiotherapy or chemotherapy, particularly because it is very important that treatments should be thorough and start early in the pregnancy. The overall prognosis is bad because pregnancy seems above all to aggravate serious forms of the disease.