Adenoid cystic carcinoma of the breast is a rare neoplasm, with only 140 cases having been reported to date. Data on 123 of these cases are reviewed herein and another case is presented in detail. Several features distinguish this type of breast cancer from more typical histologic types and suggest that it may have a unique tumor behavior. The prognosis appears to be favorable and the incidence of axillary lymph node involvement is lower. Distant metastases are uncommon, but they tend to occur without prior lymph node involvement. This lack of prognostic significance for negative axillary lymph nodes underscores the need for other prognostic markers in this disease and suggests that axillary dissection can be eliminated in most cases. Similarities to typical breast cancer include the incidence of local recurrence and the lack of effect of surgical treatment on distant metastases and overall survival. These data suggest that breast-conserving treatment may be applicable to adenoid cystic carcinoma.