Objective The aims of this study were to analyze ultrasound features of breast ductal carcinoma in situ(DCIS) and to evaluate the value of ultrasonography (US) in early diagnosis of DCIS.Methods From July 2013 to March 2015, 180 patients with histologically proven DCIS were evaluated.US features recorded included the size, shape, margins, internal echogenicity, microcalcifications, posteriorechogenicity, and blood supply. The data were analyzed and compared with mammographic and histologicfindings.Results Among 180 cases of DCIS, 168 patients had positive findings on US; the lesions were dividedinto 3 categories: (1) hypoechoic lesions with or without microcalcifications (n=94); (2) hypoechoic dilatedducts with or without microcalcifications (n=59); (3) microcalcifications alone without any other findings(n=15). Of the 180 lesions, microcalcifications were demonstrated by mammography in 128 (71%); amongthese 128 lesions, 90 were identified with microcalcifications on US. Only 80 cases (44%) manifested asmasses or asymmetric densities on mammography. The diagnostic accuracy of US and mammographywas 67% (120/180) and 69% (124/180), respectively, which can be improved to 80% (144/180) if US iscombined with mammography.Conclusion US can be used as an important tool in diagnosis of DCIS. The combination of US andmammography can improve the diagnostic accuracy of breast DCIS.