Factors influencing the determination of the available lysine content by the dyebinding method were examined in detail by utilizing Acid Orange 12, and the optimal condition for the quantitative analysis was settled. There was a highly positive correlation between the results obtained by the proposed and TNBS method. In addition to the simplicity and safetyness, the dye-binding method can reliably be adapted to the cereal products, since several types of carbohydrates seldom influenced on the measurement. The method was also able to apply successfully to the alkaline treated proteins containing lysinoalanine. The results of the animal growth study supported the usefulness of the current method.