graphy were 88.9%, 12.0%, 57.4%, 59.3%, and 42.9% and those for additional ultrasound were 94.4%, 64.0%, 82.0%, 79.1%, and 88.9%, respectively. The differences of specificity and accuracy were statistically significant (p=0.0003). On the ROC analysis, ACU were significantly different between mammography (AUC=0.586, 95% CI=0.453-0.711) and ultrasound (AUC=0.823, 95% CI=0.704-0.909) (p=0.003). Clustered calcifications with associated masses or ductal changes on additional breast ultrasound had high frequency of malignancies, 79% or 73%. In addition, 87% of malignant masses were invasive carcinomas and 45% of malignant ductal changes were ductal carcinomas in situ. Conclusion: Additional breast ultrasound examinations for the lesions with clustered calcifications on mammography can improve the diagnostic performance and significantly contribute to the specificity and accuracy of a diagnosis of breast carcinoma. In addition, the ultrasound features may predict the pathologic findings such as benignity or malignancy and invasive carcinoma or ductal carcinoma in situ.