Abstract: The objective of the present study was to examine the role of heat shock and salicylic acid in antioxidant homeostasis in mungbean (Vigna radiata L.) plant. Fifteen-day mungbean seedlings were divided into 6 groups. The first one kept in open air then harvested after 25 and 32 day post germination (negative control).The second one were exposed to 50°C for 3 h (heat stress) and then harvested after 10 days (positive control). The 3rd and 4th groups were exposed to 2 different heat shock temperature (40 and 45°C) for 1, 1.5 and 2 h. The fifth and sixth groups were sprayed with two different Salicylic Acid (SA) concentrations (0.5 or 1 mM). The groups from third to sixth were exposed to heat stress (50°C) for 3 h either directly or after week. The seedlings were harvested 10 days post heat stress. The results showed that, high temperature stress induced lipid peroxidation, electrolyte leakage and increased hydrogen peroxidase level. High temperature stress decreased catalase, peroxidase, ascorbic peroxidase activities and glutathione content. It was also found that high temperature stress induced a significant increase in endogenous SA concentration and superoxide dismutase activity. These deteriorative symptoms in the mung bean seedlings were ameliorated by heat shock treatments or SA application by decreasing lipid peroxidation and increasing catalase, peroxidase, ascorbic peroxidase, superoxide dismutase activities and glutathione content. Based on these results, it was presumed that the stress protection caused by heat shock treatments or SA application contributes to some extent to the enhanced activity of the free-radical scavenging systems.