AIM: The aim of this work is to investigate the protective effects of Ginsenoside Rb 1(Rb 1) on apoptosis induced by hypoxia /hypoglycemia and reoxygenation in cultured rat hippocampal neurons. METHODS: Apoptosis were measured by flow cytometry; Morphological changes and neuronal necrosis were examined under microscope; The leakage of lactic dehydrogenase(LDH) and the product of nitric oxide(NO) were measured. RESULTS: hypoxia /hypoglycemia cultures for 5 h and reoxygenation induced neuronal apoptosis and necrosis,and significantly increased the leakage of LDH and the product of NO. The effects were enhanced with the extending time of reoxygenation. Rb 1 could significantly decrease the percentage of neuronal apoptosis and necrosis, and reduce the leakage of LDH and the product of NO. CONCLUSION: Rb 1 had an effect of anti-neuronal apoptosis. This effect might be related to the inhibition of the activity of NO synthase and NO production.