In this investigation, three cultivars of sesame (Sesamum indicum L.) were studied for their behaviors to water limited condition. The effect of water stress on relative water content, content of proline and total soluble sugar and cell membrane injury were determined. Five drought tolerance indices were calculated based on grain yield under drought (Ys) and normal (Yp) condition. The results indicated that water deficit reduced the relative water content of the leaves and increased proline in all of the studied cultivars. The studied cultivars don’t showed a significant increase in their TSS when imposed in stress condition. Leaves of plants pre-stressed in field condition and then subjected to osmotic stress in laboratory exhibited about a % 40.5 lower membrane injury than other of not prestressed plant. The Oltan cultivar with having of the largest amount of STI and lower value of SSI and TOL recognized as a drought tolerance cultivar in compare with two other cultivars. Also, this cultivar had the highest increase in amount of proline content in water stress condition and showed not significant decrease in its leaf water content.
