Depending on the degree of difference between the breasts, as well as on the type of deformity, there are several operative techniques. If the difference is not extreme, the symmetry is achieved by inserting implants of various sizes by means of the same operative technique as in breast enlargement operation. In case of major unevenness, as well as when one breast is more loose comparing to the other, it is necessary, besides inserting the implants in the smaller breast, to perform a lifting of the looser breast as well. A special case of asymmetry is represented by Poland syndrome, characterised by a unilateral absence or underdevelopment of the pectoral muscle, absence of glandular tissue and smaller nipple, as well as changes on the fingers. The cause of this syndrome is still unknown, as well as the reason for its more frequent occurrence on the right side. It is corrected very successfully with the implant that corresponds to the size of the other breast, but often after the previous expanding the skin with the so-called tissue expander, as the existing space cannot receive a big enough implant.