Purpose To evaluate radiological findings of non-calcified ductal carcinoma in situ (DCIS) and to correlate those with histological features. Materials and Methods From July 2002 to March 2006, 22 patients with histologically-proven non-calcified DCIS were included. Mammography was obtained in 19 patients, ultrasound in 18 patients, and both examinations in 15 patients. Radiological findings were evaluated according to the Breast Imaging Reporting and Data System by American College of Radiology. Histological tumor subtype and Van Nuys classification of DCIS were assessed. Results Histological subtypes consisted of mixed type in 11 patients (50%), comedo in 4 (18%), cribriform in 4 (18%), papillary type in 2 (9%), and solid in one (5%). According to Van Nuys classification, group 3 DCIS was observed in 13 (59%) patients. In the 19 patients who underwent mammography, 13 patients presented with abnormal findings: focal asymmetry in 7 patients (37%), masses in 4 (21%), skin thickening in one (5%), and architectural distortion in one (5%). In the 18 patients who had received breast ultrasound, a mass was present in 15 (83%) patients and ductal changes in 3 patients (17%). Sixty percent of patients with masses on ultrasound had group 3 DCIS and 100% of patients with ductal change had group 1 DCIS (p = 0.017). Conclusion Diagnosis of non-calcified DCIS by mammography is not an easy task due to the lack of typical malignant calcifications or masses. High resolution ultrasound can be useful for detecting non-calcified DCIS, and ultrasound findings are correlated with histological features.