Purpose : To determine the clinical and mammographic characteristics of primary lymphoma of the breast.Materials and Methods : The clinical and mammographic records of five patients (six breasts; bilateral involvementin one patient) with histologically-proven lymphoma of the breast were retrospectively reviewed. Results : Allpatients had complained of a palpable tender mass with relatively rapid growth over a period of about 3 months. Infive cases, the mass was located in the right breast and in one case in the left. Mammography revealed diffuseincreased opacity of the entire breast in three cases, a homogeneous well-defined mass in one, multiplewell-defined masses in one, and ill-defined lobulated opacity in one. Skin thickening and architectural distortionwas seen in one case, and asillary lymphadenopathy in two. In no case was microcalcification and nipple retractionseen. Conclusion : In primary breast lymphoma, mammographic finding are non-specific. When a breast grows rapidlyand is tender, however, and mammography shows a relatively large well defined mass and associated axillarylymphadenoapathy, the possibility of primary lymphoma should be considered.