New polyanionic polymer conjugates with antitumoral activity are synthesized by chemically binding mustard type alkylating derivatives of di-(-chloroethyl)-amine and tri-(-chloroethyl)-amine, respectively, onto poly(maleic anhydride-alt-vinyl acetate). The structures of the compounds are verified by FTIR, 1 H NMR, and elemental analysis. The antitumoral activity of these polymeric drugs is evaluated in vivo using carcinosarcoma Walker 256 solid tumors in Wister rats. The conjugates exhibit antitumor regression (ATR)