In the course of a systematical studies on halogenoethylhydrazides of natural alpha-aminocarboxylic acids and their derivatives, N,N-di(2-bromoethyl)hydrazides of glycine, valine, lysine, phenylalanine, L- and D,L-alanine, leucine, isoleucine and cystine were synthesized. It was shown that N,N-di(2-bromoethyl)hydrazides of amino acids with deblocked amino groups are comparatively toxic and unstable, while the N alpha-protected compounds are stable, nontoxic even at a dose of 625 mg/kg and with a high antitumour effect: 70-92% suppression of tumour growth at a dose of 75 mg/kg.