We present a study made during 4 years (1992-1996), which pursued the underlining of the atypical intraductal hiperplasias (A.I.D.H.) lesions, met isolated or in the association with mamar carcinoma. Our study included a 188 number of the breast tumors, among: in the 23 cases we established the existence of the modification by the A.I.D.H, type at the fibrocystics disease associated or not with the other benign diseases of the breast (fibroadenosis, intraductal papiloma) and in the 63 cases there were the modification by the AIDH associated with in situ or invasiv carcinoma. Epithelial hyperplasia is frequently associated with the fibrocystic changes, being included in the category of fibrocystic or proliferating modifications. The synonymous terms used for the epithelial hyperplasia are the hiperplazia ductala, or the epitelioza, or the papilomatosis The last two are suggested by the proliferation possibility (papillary or linear) of the epithelial or the mio-epithelial cells. Regardless of the microscopic aspect of the lesion, that should be acknowledged and treated as it is, due to the increased risk of the development of a carcinoma later on, and also due to the ratio of association between the modification and the mammary carcinoma. The risk of occurrence of subsequent carcinoma is augmented in the presence of the epithelial atipii and also increases in the presence of a mammary carcinoma at the relatives of the first rank (1.3). In this context, the importance of the differential diagnosis between the simple intraductal hyperplasia and the atypical one, the difficulty of differentiation from intraductal carcinoma in some cases, and finally the association with an increased risk of subsequent occurrence of carcinoma, constitute into sufficient arguments to consider this topic separately.