The microscopic differential diagnosis of malignant lymphoma and benign lymphoid infiltrates in the lower female genital tract may be difficult. We have reviewed the clinical and pathological features of 16 lymphoma-like lesions of the cervix (10 cases), endometrium (five cases), and vulva (one case) and compared these features with those of malignant lymphoma. One patient with a cervical lesion and one with a vulvar lesion had infectious mononucleosis. Microscopic examination of the lesions revealed an infiltrate of large lymphoid cells with prominent mitotic activity, including cleaved and noncleaved follicular center cells and immunoblasts; a starry-sky pattern was present in three cases. Plasma cells, polymorphonuclear leukocytes, and small lymphocytes were present within the infiltrate in many of the cases. Immunohistochemical stains were performed in seven cases. In six they indicated the presence of polyclonal plasma cells; most of the atypical large cells did not stain for cytoplasmic immunoglobulin. In the seventh specimen many immunoblasts had cytoplasmic staining of polyclonal type. The microscopic features of the lesions differ from those of lymphomas. Surface ulceration and intralesional acute inflammatory cells and plasma cells are rarely seen in lymphomas, while a large size, deep invasion, cellular monomorphism, and prominent sclerosis were not seen in the reactive lymphoma-like lesions. Follow-up of from 6 months to 12 years was available for 10 of the 16 patients, nine of whom were treated by procedures inadequate for the cure of malignant lymphoma, and has been uneventful in all of them. The clinical and pathologic features of these cases suggest that the atypical appearances in most of them resulted from a focally florid lymphoid proliferation in association with chronic cervicitis or endometritis, or a generalized disorder of lymphoid cells such as infectious mononucleosis.