To illustrate the imaging features of non-calcified ductal carcinoma in situ (DCIS) on ultrasonography and breast MR imaging and to determine the role the imaging studies in the diagnosis and treatment decision of non-calcified DCIS. Radiologic images and clinical histories of 34 patients with histologically verified non calcified ductal carcinoma in situ (DCIS) were retrospectively studied. All patients were female and between the ages of 27 and 73 years (mean age, 47.6 years). Mammography (n=34), Breast US (n=34), and Breast MR imaging (n=29) were performed. The diagnosis of DCIS of the breast was pathologically confirmed by means of examination of the specimens obtained at surgical biopsy. We correlated radiologic findings with pathologic results. All patients were female and between the ages of 27 and 73 years(mean age, 47.6 years). The mean size was 1.7cm. DCIS is a heterogeneous disease comprising a spectrum of noninvasive malignant tumors of the breast. In the 34 patients who underwent ultrasound, 32 patients presented with abnormal findings: mass(63%), intraductal echogenic lesion(18%), irregular ductal wall thickening or nodularity(15%) and mixed pattern(4%). In the 29 patients who had received breast MRI, a mass was present in 22 patients and irregular ductal enhancement in 7 patients. Diagnosis of non-calcified DCIS by mammography is challenging. Thus, high resolution US and breast MRI can be essential to decide accurate diagnosis. Comprehensive knowledge of US and MRI findings of non-calcified DCIS of the breast can help early detection and improve prognosis.