A copper complex of $epsilon$-N-[(2-chloroethyl)carbamoyl]-L-lysine was prepared by the treatment of the L-lysine copper complex with 2-chloroethyl isocyanate in cold water. Within the L-lysine copper complex molecule, the $alpha-amino$ and carboxyl groups are bounded to $Cu^{2+}$ but the $epsilon-amino$ group is free and can react with carbamoylating agents. A potential antitumor agent, $epsilon-N-[(2-chloroethyl)$ nitrosocarbamoyl]-L-lysine was synthesized by nitrosation of this copper complex with Na $NO_{2}$ in anhydrous formic acid, followed by the passage of $H_{2}$S gas.