Abstract: The ability of olives to adapt harsh environmental conditions makes its cultivation possible where plants are frequently exposed to high temperatures and scarcity of water. As the annual crop evapotranspiration far exceeds the rainfall in Kuwait, supplemental irrigation is essential for plant production. Under this conditions, efficient irrigation strategy is crucial for sustainable olive production. Therefore, the irrigation study comprising of five cultivars (Arbequina, Barnea, Coratina, Koroneiki and UC13A6) and three levels of irrigation (50, 75 or 100% of ET_p) was conducted during 2006 - 2008. The results showed that none of the cultivars was adversely affected by even the highest water stress level (50% of ETp), indicating that these cultivars were able to tolerate severe and prolonged drought conditions. However, cultivar differences in plant height, stem diameter, number of branches and weight of pruned materials were significant at P < 0.01. Overall, cultivars Barnea and Coratina exhibited better adaptability to deficit irrigation and grew more vigorously than other cultivars. UC13A6 was most affected by the harsh growing conditions of Kuwait.