Ten cases of ductal carcinoma in situ (DCIS) or DCIS with microinvasion were reviewed in order to evaluate the characteristic findings of DCIS and to evaluate the extent of disease on MRI. A 1.5Tesla Signa or Horizon (GE Medical Systems) unit was used with a dedicated receive-only breast coil. The pulse sequence based on RARE was used with the fat suppression technique. After examining both breasts with a large FOV (30 cm), the affected breast alone was examined with a smaller FOV (18 cm) and larger matrix (512 x 384) with and without Gd-enhancement. DCIS showed several types of findings on MRI: linear, spotty enhancement; gathering of linear enhancement; enhanced area or mass without distortion of the surrounding tissue; and well-circumscribed mass mimicking intraductal papilloma. Compared with typical findings of invasive carcinoma, DCIS tended to be enhanced slowly. After performing MR examination in addition to mammography and ultrasonography, a more accurate diagnosis of disease extent was possible in 6 of 10 patients. MRI was useful in providing more precise information on the disease extent of DCIS, and it is considered useful in planning the type of surgery. Further study using larger series and precise pathological correlations are necessary.