Mucocele-like tumor of the breast is a rare neoplasm and only a few cases of mucocele-like tumor have been reported on in Korea. These lesions were originally considered as being benign when they were first described, but now it is believed they can be both malignant and benign, and it is even possible that they are early lesions of mucinous carcinoma. We describe here both the mammographic and sonographic findings in a patient with bilateral mucocele-like tumors that were associated with ductal carcinoma in situ and mucinous carcinoma.