Effect of esculentoside H (EH) on release of tumor necrosis factor (TNF) from murine peritoneal macrophage (Mphi) in vitro was studied. The results showed that EH (12.5-200 micrograms.ml-1) induced the thioglycolate-broth elicited peritoneal Mphi to release TNF into supernatants in a dose-dependent manner, and higher levels of TNF activity were detected in the supernatants from EH-stimulated calcimycin-primed Mø culture. EH-induced TNF release had a different type of kinetics compared with that of lipopolysaccharides (LPS). LPS-induced release of TNF increased rapidly until 6 h after LPS stimulation, then declined gradually, while EH-induced TNF release increased gradually after EH stimulation and reached its peak at approximately 24 h later. These results suggested that the anti-tumor mechanisms of Phytolaccaceae may be related to the capacity of EH for TNF release.