Breast involvement by non-Hodgkin lymphomas is rare. We studied the morphological, immunophenotypical, and clinical features of 53 cases of malignant lymphomas involving the breast in a population of Brazilian patients. Most of the cases were of B-cell phenotype. Four of the patients with primary breast lymphomas had T-cell lymphomas, 3 had CD30-positive anaplastic large cell lymphomas, and 1 had panniculitis-like T-cell lymphoma. Most patients presented with an incidental breast mass. Secondary breast lymphoma was seen in 19 patients and most commonly occurred as part of widespread nodal disease. Two patients presented with bilateral breast involvement. The most prevalent histological subtype was also diffuse large B-cell lymphoma, followed by follicular lymphoma. This study shows that the broad morphological and immunophenotypical spectrum of malignant lymphoma of the breast occurring in a large series of Brazilian patients has many similarities with that seen in Western countries, with a higher proportion of high-grade lymphomas in both primary and secondary cases.