Abstract: Tremella polysaccharide (TP) is an important component isolated from Tremella fuciformis Berk. In this study, the in vitro effect of TP on IL-2 production was exa-mined in activated mouse splenocytes. TP(1, 5, 10 and 50 μg/ml) significantly increasedmouse splenocyte IIL-2 production. In aged mice, the level of IL-2 production is muchlower than that in young controls. TP(0.05, 0.5 and 5 μg/ml) restored the IL - 2 pro-duction to normal level as the young control. Furthermore, TP(0.05, 0.5 and 5μg/ml)was found to partly antagonize the suppressive effect of hydrocortisone on IL-2 production. The antagonistic effect of TP(5 μg/ml) on the inhibitory activity of cyclosporin Awas also observed.