The purpose of the study is to compare mammography and magnetic resonance (MR) mammography in detection and assessment of extent, of histologically proven ductal carcinoma in situ (DCIS) and to compare MR features of DCIS, with features of invasive carcinoma. Forty histopathologically proven and MR detected pure DCIS lesions were described and compared with 213 enhancing invasive carcinomas. Histopathological examination revealed 49 pure DCIS, MR detected 40 of them (81.6%). There was a good correlation between diameter measured on mammography, MR and histopathology. MR was able to detect additional foci. Ductal enhancement, a focal area or a mass were perceived in respectively 8 (20%), 8 (20%) and 24 (60%) DCIS and in 0, 6 (2.8%) and 207 (97.2%) invasive lesions. Maximal contrast enhancement after 3 minutes was seen in 60.9% of DCIS and before 3 minutes in 61% of invasive masses. Signal intensity increase of more than 100% was seen in 76.9% of DCIS and in 91.1% of invasive carcinomas. DCIS had a wash out in 53.8% and invasive carcinomas in 65.3%. MR was able to detect 81.6% of DCIS. Diameter prediction was good on mammography and MR mammography. The only MR feature exclusively seen in DCIS was ductal enhancement.