Abstract: Two free-choice feeding experiments were performed to investigate the sensitivity of chickens to its diet on the basis of amino acid balance, especially related to lysine concentration. In first experiment 21 d old broiler chicks (n = 48) were divided in to four groups (in pairs) and offered different proportion of lysine whereas in second experiment two diets with ideal and high protein was offered to broiler chicks (n = 20). Over the whole period of the experiment, birds consumed some of each diet offered, but preference was shown for the moderate or high lysine diet over the low lysine diet. Growth rate reflected total lysine intake. The birds offered the choice between Ideal Protein diet and High Protein diet consumed about 2.5 times as much of the Ideal protein diet as of the imbalanced diet. So, the broilers are instinctively prone to balanced nutrition and high amino acids are on their priority during various strategic choice feeding programs.