Superoxide dismutase (SOD, E.C.188.8.131.52) converts superoxide to hydrogen peroxide, therefore important in prevention of oxygen toxicity produced by several environmental stresses. In the present work, the effect of water deficit on the activity of SOD isoenzymes in roots and shoots of 10 day-old seedlings of seven wheat cultivars was studied. Bread wheat varieties showed different responses, while a general decrease in the SOD isoenzyme activity was observed in a durum variety. The obtained data suggest that: i. Under similar stress conditions, mitochondrial and cytosolic SOD isoenzymes respond differently, ii. Drought stress may increase isoenzyme activity of SOD in the tolerant and adaptive varieties, while causing a decrease in the sensitive varieties.