OBJECTIVE: To study the characteristics of protein phosphorylation of p65, IkappaBalpha and IkappaBepsilon in lymphocytes of rats in the progress of aging and the the interventional effect of Epimedium flavonoids (EF). METHOD: We chose the lymphocytes derived from SD rat spleen. We divided the SD rats into five groups i. e. 4 months (4 m), 27 months (27 m), the 27 m EF treated group (27 m + EF), and we also observed the whole interventional effect of PDTC (a NF-kappaB inhibitor) on old rat groups (27 m PDTC, 27 m PDTC + EF ) when IkappaBepsilon, IkappaBalpha were detected. Through the western-blotting analyses, we studied the entire characteristics and distinctions of phosphorylation expression in molecules related to NF-kappaB signal transduction pathway p65, IkappaBepsilon and IkappaBalpha in lymphocytes across the age spectrum of rats in aging. We also observed the whole interventional effect of EF on lymphocytes of old rats. RESULT: With the increasing of age, the mean level of phosphorylation expressions of p65, IkappaBalpha and IkappaBepsilon in rat spleen lymphocytes decreased obviously, When inhibited NF-kappaB by PDTC, there was decreased evidently, while PDTC + EF can active NF-kappaB family and the above molecules were increased to a certain extent. CONCLUSION: The phosphorylation expressions of p65, IkappaBalpha and IkappaBepsilon in rat spleen lymphocytes were not enouphe, EF have a strong effect to upregulated the expression of them during aging.