The changes in lipid peroxidation and the possible involvement of the antioxidant system in relation to the tolerance to salt stress was investigated in the cultivated beet Beta vulgaris L. cv. ansa and its wild salt-tolerant relative Beta maritinta TR 51196. The 40 days old beet seedlings were subjected to 0, 150 and 500 mM NaCl for 12 days. In B. maritima constitutive level of lipid peroxidation was lower, but activities of superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APOX), catalase (CAT) and glutathione reductase (GR) were inherently higher than in B. vulgaris cu. ansa. Compared to B. vulgaris, lipid peroxidation was also lower and the activities of SOD, POX, APOX, CAT and GR were higher in B. maritima at 150 and 500 mM NaCl. These results possibly suggest that the wild salt-tolerant beet, B. maritima exhibit a better protection mechanism against oxidative damage by maintaining a higher inherited and induced activity of antioxidant enzymes than the relatively sensitive plants of the sugar beet, B. vulgaris cv. ansa. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.