The radical-initiated terpolymerization of 3,4-dihydro-2H-pyran (DHP), maleic anhydride (MA), and vinyl acetate (VA), which were used as a donor-acceptor-donor system, was carried out in methyl ethyl ketone in the presence of 2,2'-azobisisobutyronitrile as an initiator at 65 degrees C in a nitrogen atmosphere. The synthesis and characterization of binary and ternary copolymers, some kinetic parameters of terpolymerization, the terpolymer-composition/thermal-behavior relationship, and the antitumor activity of the synthesized polymers were examined. The polymerization of the DHP-MA-VA monomer system predominantly proceeded by the alternating terpolymerization mechanism. The in vitro cytotoxicities of poly(3,4-dihydro-2H-pyran-alt-maleic anhydride) [poly(DHP-ah-MA)] and poly(3,4-dihydro-2H-pyran-co-maleic anhydride-co-vinyl acetate) [poly(DHP-co-MA-co-VA)] were evaluated with Raji cells (human Burkitt lymphoma cell line). The antitumor activity of the prepared anion-active poly(DHP-alt-MA) and poly(DHP-co-MA-co-VA) polymers were studied with methyl-thiazol-tetrazolium testing, and the 50% cytotoxic dose was calculated. (c) 2005 Wiley Periodicals, Inc.