A total of 15 cases of Japanese salivary gland lymphoma was analysed by conventional histology and also by immunoperoxidase staining of paraffin sections. The initial sites included: parotid gland (14 cases, 93%) and submandibular gland (1 case, 7%). The mean age was 59 yr, with a male to female ratio of 2.8:1. The only one patient (Case 9) with clinical evidence of Sjögren's syndrome showed the development of intrasalivary malignant lymphoma. Each lymphoma was classified according to the Working Formulation for Clinical Usage. The Working Formulation grades were 20% low, 67% intermediate, and 13% high. These neoplasms fell into six categories: follicular, small cleaved type (1 case); follicular, mixed small cleaved and large cell type (2 cases); follicular, large cell type (2 cases); diffuse, mixed small and large cell type (1 case); diffuse, large cell type (7 cases); and large cell, immunoblastic type (2 cases). Fifteen tumors were studied using a indirect immunoperoxidase method. A selected antibody panel was used, including B-cell markers (immunoglobulins, Ki-B3, L26), T-cell markers (UCHL-1 and MT1) and histiocytic markers (lysozyme, alpha 1-antitrypsin and cathepsin D). Eleven cases reacted with pan-B-marker (Ki-B3 and L26) and eight of them showed the presence of monoclonal cytoplasmic immunoglobulin (C-Ig). Following rigid criteria, monoclonal C-Ig of M kappa was demonstrated in one case of follicular, small cleaved cell type, one follicular, large cell type and two diffuse, large cell type; M lambda was demonstrated in one diffuse, large cell type; and G lambda was demonstrated in one follicular, mixed small cleaved and large cell type, and two diffuse, large cell type.(ABSTRACT TRUNCATED AT 250 WORDS)