Curcumin, an active ingredient present in Curcuma longa, was analysed for the immunomodulatory activity in Balb/c mice. Curcumin administration was found to increase the total WRC count (15,290) significantly on the 12th day Group of animals treated with vehicle alone showed results similar to that of normal animal (10,130 on 12th day). Curcumin increased the circulating antibody titre (512) against SRBC. Curcumin administration increased the plaque forming cells (PFC) in the spleen and the maximum number of PFC was observed on the 6th day (1,130 PFC/10(6) spleen cells) after immunization with SRBC. Rone marrow cellularity (16.9x10(6) cells/femur) and alpha-esterase positive cells (1,622/4000 cells) were also enhanced by Curcumin administration. A significant increase in macrophage phagocytic activity was also observed in Curcumin treated animals (P<0.001). These results indicate the immunostimulatory activity of Curcumin.