An experiment was carried out using 280 unsexed chicks of a commercial broiler breed taken randomly from a hatchery after the start of hatching. The chicks were distributed into four groups of 70 chicks each. The chicks were fed a certain type of mash feeding for 7 days as follows: The chicks of the 1st group were given the basal diet directly after hatching containing 1.2% lysine, This diet is conformed to the American feed tables of (NRC, 1994). The 2nd and the 3rd group of chicks were given the diet directly after hatching but containing 1.45%, 1.70% lysine respectively, and maintaining the rest of the nutrients as in the basal diet. The chicks of 4th group were given the diet directly after hatching, but containing 24% protein, and maintaining the rest of the nutrients as in the basal diet. After 7 days the chicks of four groups fed a broiler pellet commercial diet until the age of 42 days. The results showed the importance of adding lysine to the diet directly after hatching on the average live weight at the end of the first week, the differences were significant (P ≤ 0.05) between the chicks of the third group compared to chicks of the first group. It was also noted that the increase in lysine in the diet is better than increasing the crude protein to 24% (P ≤ 0.01) on the average live weight at the end of the first week. No significant differences were noticed among the average live weight of the chicks of all groups at the end of the experiment