In the last ten years, interest in early nutrition research has increased due to the high correlation between 7-dold weight and final weight. Sodium (Na), chlorine (Cl) and potassium (K), are essential elements in chickens in order to maintain the osmotic pressure and acid-base balance within normal values, protein synthesis in tissues, maintain extra and intracellular homeostasis and the electric potential of the cell membrane. Electrolyte balance is defined as (Na+K-Cl mEq/Kg). Many studies have indicated that sodium supplementation in the first week of life stimulated feed intake and modified weight gain and feed conversion ratio. The purpose of this trial was to evaluate the effects of different levels of sodium and electrolyte balance in pre-starter diets in three periods of 4, 7 and 10 days on performance and serum electrolytes levels in broiler chickens.