The present study was designed to investigate the effects of seed soaking with 24-epibrassinolide (24-EBL) on photosynthetic parameters and sugar content in 30 days old Brassica juncea plants under copper (Cu) metal stress. The results showed that increasing Cu concentration reduced the chlorophyll and carotenoid contents. However, Cu metal stress enhanced the reducing sugars, anthocyanin, flavonoid and xanthophyll contents. The gaseous exchange parameters like photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Et) were decreased under Cu stress, but application of 24-EBL has improved these parameters under Cu toxicity.