Cell suspensions from six Warthin's tumors (WTs) were characterized with fluorescence-labeled cell cytometry. WT lymphocyte subsets were identified with monoclonal antibodies directed against lymphocyte-associated cell antigens including T lymphocyte subsets, B lymphocytes, and natural killer (NK) cells. Results showed that T cell proportions were 58% and B cell proportions were 39%. The T cell helper:cytotoxic-suppressor ratio was 5.7:1 and the B to T cell ratio was 0.8:1. NK cells represented 1.3% of cells. When compared to peripheral blood lymphocytes (PBLs) in the same patients, statistically significant differences were noted between PBLs and WT lymphocytes in the percentage of B lymphocytes (P < .01), T cytotoxic-suppressor lymphocytes (P < .02), NK cells (P < .01), and in the ratios of B to T lymphocytes (P < .01) and T helper to T cytotoxic-suppressor lymphocytes (P < .03). Comparing these data to retrospective data on lymphocyte distribution in normal and reactive lymph nodes, the epithelial component does not appear to exert a local effect on the lymphoid component of WT.