Abstract: The discovery of the conspicuous carcinostatic property of β-p-di-(2-chloroethyl)-aminophenyl-α-alanine (Sarcolysine) has stimulated the study of cyto-active amino acids as antitumor chemotherapeutic agents. In searching for more selective tumor inhibitors and studying the relationship between chemical structures to biological activities, three isomers of Sarcolysine, namely β-m-di(2-chloroethyl) aminophenyl-α-alanine, β-p-di(2-chloroethyl) amino phenyl-β-alanine and β-m-di(2-chloroethyl) aminophenyl-β-alanine were synthesized by the reaction sequences shown in the Chinese text. All the three compounds show marked inhibitory action on the growth of a variety of experimental tumors. Compound Ⅱ_a, i.e. β-p-di(2-chloroethyl)-aminophenyl-β-alanine appears to be more effective and less toxic than Sarcolysine and is now recommended for clinical trial. The relationship between the chemical structure and the antitumor activities of such compounds was discussed briefly. The syntheses of title compounds were also reported by other authors after the publication of our preliminary communication 4 in 1959.