Wheat cultivars chosen for their cadmium (Cd) tolerance (Sonmez-2001) and sensitivity (Quality) were grown in Hoagland solution for 5 days and then they were treated with 50, 100 and 200 mu M sodium nitroprusside (SNP), a NO donor, with 9 mM Cd. Samples were taken at 24th and 72nd hours after the administration. In the present study, when examining changes in activities of antioxidant enzymes (SOD, CAT, APX, and GST) which are known as internal defense systems built up by cultivars against Cd stress, these enzymes were observed to pose different responses compared to Cd and Cd+SNP administrations. Malondialdehyde (MDA) concentration in plant tissues were also determine comparatively in order to find out lipid peroxidation. The obtained results showed that Cd stress significantly increased lipid peroxidation, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione S-transferase (GST) activities. This increase was found to be higher at various rates in different treatments in sensitive cultivar Quality compared to tolerant cultivar Sonmez-2001.