Comparison of peripheral lymphocyte subsets pre- and post-administering "Shenyang" prescription. T lymphocyte subpopulations were quantitated by flow cytometry. Samples were prepared by adding 5 μl of fluorescent monoclonal antibody of CD3, CD4, CD8 and CD161a to 100 μl of heparinized whole blood. CD3+CD4+ (T helper cell) and CD3+CD8+ (T suppressor cells) were measured and natural killer (NK) was recognized as CD3-CD161a+. Values (except for CD4+/CD8+) represent percentage (%). Data were expressed as averages and SD. * means statistic difference (P < 0.05) between pre- and post-administering "Shenyang"; I means "Shenyang" prescription group I; II means "Shenyang" prescription group II; PC means positive control group; NC means negative control group.