In this study, a pot experiment was conducted in the greenhouse conditions to investigate the drought tolerance of six Iranian grape cultivars. The experiment was factorial, based on a completely randomized design, with two factors including cultivars (‘Rotabi’, ‘Rashe’, ‘Chafte’, ‘Bidaneh Sefid’, ‘Khalili’, and ‘Laal’) and moisture treatments (40 % and 80 % of soil available water). Under drought stress, the lowest accumulation of soluble carbohydrates and proline (50.36 and 4.25 mg g^-1 FW, respectively) and the highest stress susceptibility index (2.47, on average) and growth reduction were observed in ‘Bidaneh Sefid’ cultivar. ‘Chafte’ showed a considerable growth in optimal moisture condition; moreover, this cultivar had a relatively low stress susceptibility index (0.60, on average), designated as the most tolerant cultivar to drought stress. ‘Khalili’ had the highest root weight and root volume under optimal conditions. Although this cultivar had the highest stress susceptibility index in terms of root dry weight (1.24) and root volume (1.35) after ‘Bidaneh Sefid’, but under stress conditions it had a suitable root weight, root volume and number of roots. ‘Rotabi’ and ‘Laal’ had relatively less growth under optimal moisture conditions; however, they showed a subtle growth reduction under drought stress. These results indicate that in order to introduce drought tolerant plants, stress susceptibility index and vegetative growth rate under water shortage should be considered together.