A 45-year-old woman presented with bilateral palpable breast masses, which were clinically suspicious of either mammary carcinomas or phyllodes tumors. Fine needle aspiration (FNA) study suggested low-grade lymphoma. Histological and immunohistochemical studies of an incisional biopsy specimen of the left breast lesion confirmed the diagnosis of low-grade B-cell lymphoma. Computerized tomographic scans of chest and abdomen revealed multiple lymphadenopathy in the mediastinum and intra-abdomen. After receiving chemotherapy, marked reduction in size of both breast masses and the internal lymph nodes was observed. Primary lymphomas of the breast are rare, particularly those with bilateral involvement. FNA is an inexpensive diagnostic tool for breast lumps that can reliably distinguish carcinoma, sarcoma and lymphoma. Although it is often difficult for the cytological study to differentiate low-grade lymphoma from reactive lymphoid proliferation, FNA results in combination with clinical and radiological studies (triple testing) generally provide guidance for appropriate investigations, and helps avoiding unnecessary major operation.