Kinetical study was carried out in the base-catalyzed racemization reaction of N-benzoyl anilide derivatives of six neutral amino acids, such as alanine, α-aminobutyric acid, valine, leucine, phenylalanine and phenylglycine. From the comparison of rate-constants thus obtained, it was concluded that the susceptibility of amino acids tested to the racemization may be expressed in thrm of acidity of α-proton related to the electronnegativity of alkyl-, aralkyl- and aryl-side chains at α-carbon.