Tissue expansion in breast reconstruction is a invaluable alternative surgical procedure. The advent of permanent expander prosthesis eliminated a second operative procedure for removal of the expander and replacement with another permanent implant.
 When we consider the choice of method for breast reconstruction, we have to take account of the extent of mastectomy, past-medical history of the patient, timing of operation, and patient's motivation. It is still accepted that autogenous breast reconstruction is the best choice of the method. As autogenous breast reconstruction increases in popularity, however, it requires longer operation time, more complicated technique, and careful attention to donor site. Autogenous breast reconstruction is also not good candidate for the patients who have diabetes, vascular disease, smoking, obesity, previous history of cesarean section, or further pregnancy planning. 
 We have performed 10 immediate breast reconstructions after modified radical mastectomy using the permanent expander prosthesis, manufactured by Mentor corporation. Among these cases, 8 patients underwent cesarean section and 2 patients planned pregnancy. Although this method has advantages of simple technique, minimal morbidity, and low cost, it has some limitations for orientals. First, it is inevitable in superior fullness of the reconstructed breast because of round orientals. First, it is inevitable in superior fullness of the reconstructed breast because of round shape of the expander. Second, it is difficult to get ptotic breast because of thick and inelastic characteristics of oriental skin. Third, the ratio of expander base to projection is not appropriate for orientals because of their smaller chest size. We experienced 2 cases of spontaneous deflation for its manufactural defect itself. In our experience, we would like to suggest that new type of permanent expander prosthesis should be innovated