PURPOSE: The purpose of the study is to determine the mammographic and ultrasonographic features of thebreasts with partial mastectomy and irradiation. MATERIALS AND METHODS: The authors reviewed the serial studies of23 patients who had partial mastectomy and irradiation. Mammogram and ultrasonogram were perfomed every 6 monthsafter surgery in all patients. Sixteen of 23 patienst took mammogram and ultrasonogram 1 month after surgeryadditionally. We evaluated skin thickening, edema, new calcification, and postoperative scar. RESULTS: Skinthickening was observed in all patienst at initial study after surgery and were most pronounced 6 months aftersurgery. In the most of patients, increased breast density suggesting edema was seen at the initial study aftersurgery. Skin thickening and edema were most pronounced 6 months who had retumed to normal state 18 months aftersurgery in 3 of 5 patienst who had serial studies until 18 months after surgery. Scars were noted in 20 of 23patients and 9 of 20 patients had scars 6 months after surgery. The postoperative changes including skinthickening, edema, and scar were most pronounced at 6 months after surgery and had retumed to normal at 18 monthsafter surgery. CONCLUSION: We conclude that postoperative imaging should be obtained 6 months after surgery,followed by every 6 month intervals, which can be effective in differentiating postoperative scar from recurrentcarcinoma and can avold invasive studies.