Heat stress is the important problem for rice production because it mainly reduces photosynthesis and pollen viability. This study evaluated photosynthetic capacity and pollen germination in rice (Oryza sativa L. cv. Pathum Thani 1) under heat stress condition after foliar spraying of 24-epibrassinolide (EBR) at 78 days after sowing (R2 stage). One week after EBR application, the rice plants were exposed to 40D/30N°C for seven days. The result demonstrated that EBR had high effi ciency in increasing of net photosynthetic rate, stomatal conductance and transpiration rate. Moreover, in vivo pollen germination and seed setting of EBR-treated plants were higher than heat-stressed control plants without EBR. On the other hand, heat stress caused the depression of photosynthesis and the reduction of pollen germination and seed setting. Consequently, these results confi rm that EBR could alleviate the detrimental effects of heat stress on plant growth by improving photosynthetic efficiency and pollen germination and enabled rice to withstand high temperature condition.