The histopathological and immunohistological features of non-Hodgkin's lymphoma limited to the Waldeyer's ring were studied in 22 Japanese patients using a panel of T- and B-cell markers on paraffin-embedded sections. All cases showed a diffuse growth pattern. Twenty cases were B-cell lymphomas and two were T-cell lymphomas. In contrast to the primary malignant lymphomas of the nasal cavity and paranasal sinuses, in which T-cell neoplasms are more frequently seen, the majority of the primary Waldeyer's ring lymphomas were B-cell neoplasms. Sixteen of the 20 cases of B-cell lymphoma were centroblastic lymphomas, and the monomorphic variant comprised the majority of these; the other three B-cell lymphomas were immunocytomas. Two of the T-cell lymphomas showed morphological features of angiocentric lymphomas.