Research into breast diseases is developing in all directions. In particular, there has been great progress in the fields of cytology, radiology, isotope studies, thermography and ultrasonography. The diversity of these methods reflects the complexity of the diagnosis. No one method is infallible. We therefore consider that the frozen section examination should be an integral part of a breast surgery. It should be the decisive step in the operative strategy, as breast surgery is associated with important consequences: re-operation is always difficult and a radical operation is irreversible. Frozen section examination can reduce these risks.