The effects of salinity on the growth, relative water content (RWC), chlorophyll content, inorganic ions, proline accumulation, lipid peroxidation and antioxidant enzymes, superoxide dismutase (SOD), ascorbate peroxidase (APOX), and catalase (CAT) of 3 cucumber (Cucumis sativus L.) cultivars (Cengelkoy, Anadolu F1, and Beith Alpha) were investigated. Cucumber cultivars were grown in perlite culture and irrigated with half-strength Hoagland nutrient solution for a period of 35 days under controlled conditions. After this period, seedlings were treated with 150 mM NaCl solution and the plants were harvested on day 7 and day 14 of salt treatment. The fresh and dry weights, RWC, inorganic ions, total chlorophyll, proline and malondialdehyde (MDA) content, and SOD, CAT, and APOX activities were determined. In general, the applied salinity affected all of the considered parameters depending on the duration of salt treatment and the cultivars analyzed. Proline content also increased with salinity, but accumulation of proline was lower in Cengelkoy than in the other cultivars. The results suggest that the protection mechanism against oxidative damage due to induced activity of antioxidant enzymes may be better in Cengelkoy than in Beith Alpha or Anadolu F1. The higher K+ concentrations, RWC, total chlorophyll content, and SOD, CAT, and APOX activities, together with the lower MDA, proline content, and Na+ and Cl- concentrations detected in Cengelkoy might make this cultivar more salt-tolerant than Beith Alpha or Anadolu F1.