Purpose : To evaluate the specific findings of infiltrating ductal carcinoma from the ductal carcinoma insitu(DCIS) and to differentiate from the atypical ductal hyperplasia (ADH). Materials and Methods : Fifty breastlesions in 48 patients including thirty-six breasts of 36 patients with infiltrating ductal carcinoma, fourteenbreasts of 12 patients with DCIS, and nine breasts of 7 patients with ADH were examined with FLASH technique usingGd-DTPA. We evaluated the maximal amount, the speed, and the pattern of enhancement after intravenous injection ofGd-DTPA (0.16mmol/kg body weight). Also we evaluated the diagnostic accuracy in the patients with breast cancer.Results : The maximal amount of enhancement were 1,161.84$pm$394.44 NU in infiltrating ductal carcinoma,982.11$pm$458.35 NU in DCIS, and 1,035.94$pm$305.20 NU in ADH. The speed of enhancement was 827.33$pm$384.20 NU withinthe first 1 minute with a sudden increase in signal intensity after injection and a much slighter increasethereafter in infiltrating cuctal carcinoma. DCIS showed in creasing signal intensity within the first 2 minutes(749.70$pm$487.36 NU), and ADH showed significant increased enhancement (765.40$pm$313.61 NU) at 3 minutes afterinjection of Gd-DTPA. The patterns of enhancement were focal with irregular margins in infiltrating ductalcarcinoma and irregular peripheral enhancement in DCIS and ADH. However, absent or extreme delayed enhancement atthe central portion of the tumor was more frequently seen in infiltrating ductal carcinoma rather than DCIS orADH. Conclusion : Gd-DTPA enhanced dynamic MRI was valuable in the diagnosis of breast cancer and indifferentiating DCIS from ADH. Furthermore, it was effective in analyzing the extension of breast carcinoma,multiplicity, and bilaterality of breast carcinoma.