Breast lymphoma is a rare form of non-Hodgkin lymphoma (NHL). However, its clinicopathologic features, treatment, patterns of failure and prognosis remains unclear. We reviewed the clinicopathologic features, treatment variables, failure patterns and the clinical outcome of all cases of breast NHL diagnosed in three institutions in Taiwan between 1984 and 2006. The diagnosis, based on the criteria proposed by Wiseman and Liao, was primary breast lymphoma (PBL) in 23 patients and secondary breast lymphoma (SBL) in 19. Diffuse large B-cell lymphoma was the predominant histological type of both. Among patients with PBL, 18 received chemotherapy and radiotherapy, 3 received chemotherapy alone and 2 received radiotherapy alone. In contrast, all 19 patients with SBL received chemotherapy alone. At a median follow-up of 4.4 years, patients with PBL had a significantly better 5-year event-free survival and overall survival. The contralateral breast was the predominant site of recurrence for patients with PBL. In multivariate analyses, young age and stage IIE disease were significantly associated with poorer prognosis of PBL. Our results indicate combined modality treatment results in a favourable outcome for patients with PBL. Further investigation of underlying mechanisms of young age- and stage IIE disease-related poor prognosis in patients with PBL is needed.