Objective : To explore the mechanism and effects of panax notoginseng saponins (PNGS) on pertussis bacilli-induced brain edema in rats . Methods : The protective effect was studied of PNGS and mannitol (MN) on brain edema induced by injecting purtussis bacilli (PB) into the left internal carotid artery in rats . Forty Sprague- Dawley rats were randomly divided into four groups . Group 1 (NS , n = 10) , as control ;Group 2 (PB , n=10) , pertussis bacilli control ; Group 3 (PNGS , n=10) , PB + PNGS ; Group 4 (MN , n = 10) , PB + MN . The brain water content ( WC) , Evan's blue (EB) content , and the concentrations of malondialdhy (MDA) , superoxide dismutase (SOD) and TNFα were determined. Results : The levels of TNFα in left brain tissues of PNGS group were significantly lower than those of PB and MN groups ( P <0. 05) . WC ,and EB content and MDA concentrations in left brain tissues of all treat groups were significantly lower compared with that of the PB group , but SOD activity in left brain tissues of all treat groups were significantly higher than that of the PB group( P <0. 05) . WC , EB contents in left brain tissues of PNGS group were significantly lower than those of MN group (P<0. 05). Conclusion : The PNGS have a therapeutic effect on pertussis bacilli-induced brain edema in rats , and the effects are related to the inhibitory effect on lipid peroxidation , and decreased the release of TNFα.