The clinicopathologic, mammographic, and sonographic findings in patients with pure ductal carcinoma in situ (DCIS) were assessed by estrogen receptor (ER) expression. After institutional review board approval, patients with pure DCIS evaluated from January 1996 to July 2009 with known ER status and available imaging were identified. Images were reviewed as per the ACR BI-RADS(®) lexicon (4th edition). Clinical, pathologic, and imaging characteristics were analyzed by ER status using t test, Chi square test, and Fisher's exact test. Of 1,219 patients with pure DCIS and known ER status identified, 1,187 with complete data were included. Mammography was performed in all 1,187 patients and sonography in 519 (44 %). There were 972 (82 %) patients with ER-positive and 215 (18 %) with ER-negative disease. ER-negative DCIS was more likely to be high grade (93 vs 44 %, p < 0.0001), associated with comedonecrosis (64 vs 29 %, p < 0.0001), and multifocal (23 vs 15 %, p = 0.009). On sonography, ER-negative DCIS was more likely to be visible (61 vs 46 %, p = 0.004), larger (mean size, 2.3 vs 1.6 cm, p = 0.006), and show posterior shadowing (53 vs 28 %, p = 0.006). Mastectomy was more frequently performed for ER-negative DCIS (47 vs 37 %, p = 0.008). Palpable DCIS was visible on sonography in 55 % of cases and mammography in 81 %. Compared with ER-positive palpable DCIS, ER-negative palpable DCIS was larger and more likely to be visible on sonography. Compared with ER-positive noncalcified DCIS, ER-negative noncalcified DCIS was less likely to be visible on mammography. ER-positive and ER-negative pure DCIS have different clinicopathologic and imaging characteristics. ER-negative DCIS is associated with worse prognostic factors than ER-positive DCIS. On sonography, ER-negative DCIS is more frequently visible than ER-positive DCIS, tends to be larger, and more frequently demonstrates posterior shadowing.