Object To study the effect of emodin, the active principle in rhubarb on the secretion of TNF ?, IL 1, IL 6, and [Ca 2+ ] i by rat peritoneal macrophage under different conditions Methods Hypernomic inflammation models of isolated rat peritoneal macrophage were prepared by lipopolysaccharide excitation and the levels of [Ca 2+ ] i and the proinflammatory cytokines TNF ?, IL 1 and IL 6 secreated determined by fluorescence spectrophotometry and bioassay Results Emodin showed a dual regulatory effect on the secretion of proinflammatory cytokines and [Ca 2+ ] i Conclusion It seemed that emodin has a biphasic immuno regulatory effect