OBJECTIVE. The purpose of this study was to evaluate the differential radiologic findings of pure mucocele-like tumor and mucocele-like tumor associated with atypical ductal hyperplasia (ADH) or malignancy of the breast according to BI-RADS and sonographic cystic mass classification. MATERIALS AND METHODS. During a 10-year period, 72 mucocele-like tumors in 68 women were diagnosed histologically at three institutions. We retrospectively reviewed the mammographic (n = 69) and ultrasound (n = 72) findings of the 72 lesions according to the BI-RADS lexicon. The radiologic findings were correlated with the pathologic results. RESULTS. Mammography showed 53 lesions had calcifications without (n = 39) or with (n = 14) a mass. Calcifications of intermediate concern or associated with higher probability of malignancy were found more frequently in mucocele-like tumors associated with ADH or malignancy than in pure mucocele-like tumors (92.3% vs 62.9%, p = 0.019). At ultrasound, 69 of the mucocele-like tumors (95.8%) were seen as a cystic mass. Cysts with thick septations, clustered cysts, and complex masses were more frequently seen in mucocele-like tumors associated with ADH or malignancy (89.7% vs 32.5%, p < 0.001). The positive predictive value for BI-RADS category 4 was 13.3% (95% CI, 6.9-24.2%) and was 50% for BI-RADS category 5 (95% CI, 15-85%). CONCLUSION. Mucocele-like tumors associated with ADH or malignancy were more frequently seen as clustered cysts, cysts with thick septations, and complex masses associated with calcifications of intermediate concern or higher probability of malignancy. BI-RADS can be used in the management of mucocele-like tumors. © American Roentgen Ray Society.