The present invention provides an anti-icing/de-icing system and method using ultrasound waves for an external surface of a structure likely to be iced, such as an aircraft wing or engine nacelle, and such a structure incorporating this system. The system comprises a plurality of piezoelectric transducers with which the structure is fitted, opposite this external surface, and this system is such that it comprises scanning devices at least one matrix of elementary meshes predefined in this surface in relation to an even arrangement of a group of these transducers, these scanning devices being able to focus the waves emitted by all or some of the transducers of the or each group on these meshes one after the other, via signal summing devices coupled to these scanning devices and able to produce, for each mesh, a summation of the signals obtained from the transducers emitting these waves.