The effect of different concentrations of dietary Na from three Na salts (NaCl, NaHCO3 and Na2SO4) was assessed in two experiments carried out on broiler chickens aged from 1 to 35 days. In Exp. 1, diets were supplemented with 0.15, 0.20 and 0.25% Na, which increased the average Na content of the diets to 0.19, 0.24 and 0.30% respectively. In Exp. 2, the amounts of selected Na salts (NaCI and Na2SO4) were reduced and the estimated Na contents of experimental diets amounted to 0.10, 0.13, 0.15 and 0.19%. In view of the risk factors for the development of foot pad dermatitis, our aim was to find an optimum source of Na and to keep dietary Na intake at the minimum level sufficient to support normal growth and acceptable slaughter quality. The present results suggest that the amount of Na required for the undisturbed growth of broilers and adequate feed conversion is not less than 0.15% of additional Na in the starter period (1-14 d), and not less than 0.11% in the grower period (until day 35). Higher dietary Na levels did not lead to further production advantages, and were found to increase the moisture content of droppings. Dry matter concentration of excreta was also affected by Na source. In comparison with NaHCO3, Na2SO4 seemed to be a better alternative for NaCl. Na2SO4 also tended to surpass NaHCO3 as a dietary alternative for NaCl in terms of feed utilisation during the starter period. The applied additional Na levels (0.25 and 0.15%) and Na sources had no effect on the sensory profile and composition of breast meat.