Abstract: The aim of present study was to get further information on the ability of drought stress applied to retard senescence and to frustrate inhibitory effects of drought-stress via comparing two canola genotypes differing in drought tolerance. The objective of this work was to evaluate the effects of the drought stress (control, -0.5, -1 and -1.5 Mpa) on two canola genotypes (Okapi and RGS). The experiment was factorial with four replications at experimental greenhouse at Center of Agriculture Research-Shahed, Iran, during 2006-2007. Morphological parameters of root and shoot dry weight, proline content osmolyte and enzyme activities of Ascorbate peroxidase (APx), Guaiacol peroxidase (GAx) and Catalase (Cat) in shoot and root of tissues canola genotypes were highly significant differences for main and interaction effects of two factors (Drought (D) and Genotype (G)) studied. Drought decreased the roots and shoots dry weight of canola plants and this effect was particularly significant at high level of stress. So, results indicated that proline content, ascorbate peroxidase (APx) and Guaiacol peroxidase (GAx) and Catalase (Cat) activity in root and shoot increased with enhancement of drought stress in the two genotypes. Of course, the proline content and antioxidant activities in Okapi genotype were more than RGS genotype. These results showed that Okapi genotype tolerated drought stress than RGS with increasing of proline content and antioxidant activities including GAx and APx. Shoot always maintained higher level of free Catalase (CAT) contents than the root. Therefore, the evaluation of both antioxidant enzymes and proline content can be suggested for Mechanisms of drought stress tolerance.