Amyloidosis is rarely considered in the differential diagnosis of breast masses. During the past six years, 27 women with primary (24) and multiple myeloma-associated (three) amyloidosis (AL amyloid) were evaluated at our center. In five of these patients, amyloid was demonstrated on microscopic examination of breast tissue. The clinical presentations were similar to fibrocystic breast disease in two cases and malignancy in two others. Amyloidosis of the breast may be more common than previously recognized, especially considering the predilection of amyloid for depositing around fat cells. Therefore, pathologic examination of nonmalignant breast tissue should include Congo red staining and viewing under polarized light.