The classification Bi-Rads (Breast Imaging Reporting and Data System). Of the ACR (American College of Radiology) is the system of classification of the radiological images, recommended for the breast cancer screening, and allowing to propose an adapted action to be taken according to this classification of ACR 1 to ACR 5 depending on the probability of malignancy. The lesion ACR IV corresponds to an indefinite and suspect anomaly with probability of malignancy of 10 – 90 %. This disparity urged us to realize our study. It is about a retrospective study of 181 patients spread over 5 years, from 2009 till 2013, led in the service of gynecology-obstetrics I of the Hospital center Hassan II Fes Our objective is to report the histological results of the breast lesions classified radiologically ACR4 with the aim of estimating the radio-histological correlation and improving the action to be taken. The breast pathology seems to affect the feminine population at any age with a peak of frequency between 40 and 50 years. The palpation of a nodule is the 1st motive leading a consultation at our patients with 78 % of the cases. All our patients benefited from the couple echo-mammography then from an anatomopathological evidence by various techniques. We noted a clear predominance of the benign lesion with a 62 % rate against 29 % of the malignant lesion and only 9 % were intermediate. The adénofibrome is the histological result found most with 30 % of the cases, the infiltrating carcinoma canalaire remains the leader of the malignant lesion with 17 % of the cases.82 % of our patients were operated among which 69 % benefited from a tumerectomie and 13 % of a mastectomy. Through a review of the literature, our results seem to join those of the other studies. However because of the significant number of the useless surgical operations, a sub-classification in ACR4a, b and c seems to be more adapted.