A green-house experiment was conducted for 90 days according to a completely randomized block design. The treatments used were as follows: five levels of sodium, 0.0; 4.0; 40.0; 400.0; 4,000 (all in ppm) added as NaCl and Na2SO4, respectively, to a HOAGLAND & ARNON complete nutrient solution. These were used individually as nutrient media for two cotton plant cultivars, namely '9193' and 'c-71', thus comprising a total of 20 treatments wich were replicated four times each. The results showed an increase in dry matter production of the plants as a result of the addition of 4.0 ppm of sodium whereas 400.0 ppm and 4,000 ppm had a decreasing effect. The drymatter production of the cultivar '9193' interacted negatively with the chloride íon.