In this research, we investigated the response of sunflower cultivars to drought stress under both in vitro and in vivo conditions. Murashige and Skoog basal medium supplemented with a range of polyethylene glycol (PEG-1000) concentrations was used for in vitro drought screening. Results from both in vitro and in vitro experiments showed that plant growth decreased with increasing PEG concentrations. In addition, there were differences between the cultivars in terms of their response to drought. The significant correlations between in vitro (except number of roots) and in vivo characters indicate that an in vitro approach could be useful in screening and selecting for drought response prior to field trial. As a result, all in vitro characters measured (except number of roots) could give clues for performance of sunflower genotypes against drought in vivo.