In the present investigation the synthesis of p-[bis-(2-chloroethyl)aminomethyl]-phenyl-alanine dihydrochloride (IIIa, designated as AT-290) has been described.As can be seen from the structure, it is derived from the nitrogen mustard HN₂(Ⅳ R=H) by substituting one hydrogen atom of the methyl group with the p-phenylalanine moiety.Since the para position of the benzene ring is of importance in a number of metabolic functions of phenylalanine, the meta-and oTtho-isomer of Ⅲa, namely,m-[bis-(2-chloroethyl)amino-methyl]-phenylalanine dihydrochloride (Ⅲb, AT-582) and o-(bis-(2-chloroethyl)aminome-thyl]-phenylalanine dihydrochloride (Ⅲc, AT-581) were also synthesized.