The N~-(2-chloroethyl)-N-nitrosocarbamoyl derivatives of H-Pro-Lys (X)-Pro-Val-NH,(X: tert- butyloxycarbonyl, formyl,(2-chloroethyl) nitrosocarbamoyl) were synthesized. It was found that the bis-substitution of the urea N3 in these derivatives does not decrease the antitumor activity influenced mainly by the nature of the carrier molecule as a whole.