Drought is one of the most significant abiotic stresses that reduces the yield of crops and global agricultural products. Along with increasing drought stress, its destructive effects on urban landscape is getting more realised. Nowadays, plants used in landscape design tried to be drought resistant, which is a major criteria for selection of species in dry regions. Vitex genus comprises 250 species distributed all over the world. One of the spesies, chaste tree ( Vitex agnus-castus ) , is a deciduous shrub, widespread in the Mediterranean region and the central Asia. N-acetyl-5-methoxy tryptamine (melatonin), a polyotropic molecule, powerful scavenger of free radicals, has a protective role in growing tissues, especially reproductive tissues, and preserving the plant. In order to study the effect of drought stress on chaste tree and the role of melatonin in reducing this effect, a factorial experiment based on a completly randomized block design with four replications was performed. Drought treatment applied at three levels 0, -2.5 and -5 bar and melatonin treatment at five levels of 0, 25, 50, 100 and 200 ?M. This experiment was conducte in a hydroponic system. The results of this study were report in two periods of 20 and 40 days after drought stress. Drought stress at -2.5 bar had no significant effect on ion leakage (IL), leaf relative water content (RWC) and superoxide dismutase (SOD) activity enzyme in comparison with the control sample. In addition, proline, catalase (CAT) and ascorbate peroxidase (APX) activity enzymes increased significently. By increasing drought duration from 20 to 40 days, height, IL, carotenoid content, APX and CAT increased and the Fv/Fm, chlorophyll b and a, malondialdehyde content (MDA), RWC and SOD activity decreased. By increasing drought intensity up to -5 bar, the measured factors declined compared to the control sample. All of these results suggests that the plant tolerates mild drought stress up to -2.5 bar, and severe drought decreases the growth and lead to the decline of the plant. The application of 100 ?M melatonin had the best effect on vegetative, physiological, photosynthetic, biochemical factors and proline accumulation. In general, this plant does not resistant to drought conditions and the use of melatonin has not been able to protect the plant against the high drought stress level. Key Words Polyethylene glycol 6000, Hydroponics, Drought stress, Melatonin, Urban landscape