BI-RADS is a system of assistance to the drafting of the reports more and more used in the world and soon directly implemented on mammography and ultrasound units. The categories of evaluation of the BI-RADS allow a clear synthesis of the descriptive data resulting from the use of the lexicon and invite the radiologist to a reasoned, objective and less intuitive step. They give an action to be taken and responsibility to the radiologist and the referring physicians in the assumption of the patients. The 4th edition of the BI-RADS mammography appeared in 2003, and is now associated with the first editions of the BI-RADS ultrasound and MRI.