Four experiments were conducted to determine whether fluctuations in dietary electrolyte level (milliequivalents Na+K-Cl per kilogram) or different dietary sodium chloride levels would affect performance, water intake, or excreta moisture of chickens fed semduramicin vs nonmedicated controls. In all experiments, male commercial broiler chicks were used, and all diets were fed with and without 25 mg semduramicin/kg diet. The basal diets were based on corn, soybean meal, and poultry oil. Experiments 1, 3, and 4 were conducted using male broiler chicks in battery brooders to 18 d of age. In Experiment 1, six electrolyte levels were fed [basal (0.2% Na, 0.33% Cl, 1.10% K); basal plus 0.1% Na (from sodium chloride); basal plus 0.1% K (from potassium chloride); basal plus 0.2% Na (from sodium carbonate); basal plus 0.34% K (from potassium chloride); basal plus 0.15% Cl (from ammonium chloride)]. There were no significant changes in BW gain, feed consumption, or feed conversion ratio caused by any dietary treatment. Water consumption was not affected by the inclusion of Na, Cl, K, or electrolyte levels, but excreta moisture was affected. The highest and lowest excreta moisture levels came from chicks fed the lowest chloride levels. There were no significant dietary effects on serum Na, Cl, or K by dietary electrolytes or semduramicin. Experiment 2 was conducted with triplicate floor pens of 33 male broilers each for 42 d with four electrolyte levels [basal (0.2% Na, 0.34% Cl, 1.03% K); basal plus 0.1% Na (from sodium carbonate); basal plus 0.1% Cl (from ammonium chloride); basal plus 0.18% K (from potassium carbonate)]. Increasing electrolyte level had a significant effect on BW gain at 35 d but not at 42 d [mainly because of differences in K (1.943 kg at 35 d) vs Cl (2.013 kg at 35 d)]. At 42 d, there were no differences in growth because of N, K, Cl, or semduramicin. Potassium supplementation caused a significant increase in litter moisture (P = 0.031). Semduramicin did not affect litter moisture (P = 0.892), nor were there significant semduramicin interactions with Na, K, Cl, or semduramicin. The basal diets in Experiments 3 and 4 were identical to the basal diet in Experiment 1 except there was no sodium chloride added. The diets fed in Experiment 3 contained 0, 0.1, 0.2, 0.3, or 0.4% added sodium chloride. The diets fed in Experiment 4 contained 0.1, 0.3, 0.5, 0.7, and 0.9% added sodium chloride. The results of Experiments 3 and 4 show that about 0.4% added sodium chloride is necessary to achieve maximum growth and feed conversion. It is clear that semduramicin had no significant effect upon the variation observed in any of the variables measured.