OBJECTIVES: To determine the effects of magnesium sulfate on Caspase-3 and Vascular endothelial growth factor (VEGF) of human umbilical vein endothelial cells (HUVECs) under presence or absence of Tumor necrosis factor (TNF-alpha). METHODS: HUVECs were isolated from normal term umbilical cords and cultured in several physiolo gically relevant concentrations of magnesium sulfate with or without exposure of TNF-alpha. The concentrations of VEGF and caspase-3 were estimated by colorimetric assay and ELISA assay, respectively. RESULTS: The concentration of VEGF in HUVECs significantly increased in the presence of TNF-alpha compared with in the absence of TNF-alpha. However, the concentration of VEGF did not show significant difference in several concentrations of magnesium sulfate concentrations with addition of TNF-alpha and it showed the lowest concentration under 4 mM and 8 mM of magnesium sulfate concentration without addition of TNF-alpha. The concentration of caspase-3 in HUVECs did not show statistically significant difference with the addition of TNF-alpha and magnesium sulfate. CONCLUSION: TNF-alpha induce HUVECs to stimulate the VEGF, and magnesium sulfate might not have the effects on the expression of VEGF with addition of TNF-alpha However, the concentration for treatment of magnesium sulfate inhibits the expression of VEGF without addition of TNF-alpha. Magnesium sulfate might not have an effect of the expression of caspase-3 with or without addition of TNF-alpha.