AbstractCopolymers of ethylene and vinyl acetate (E‐VA) of a certain composition can be used for the improvement of impact properties (elasticisation) of PVC as well as under certain conditions (grafting) for the preparation of flexible PVC (plasticisation). Products of interesting properties are prepared by blending E‐VA (up to ∼ 12%) with PVC or more advantageously by grafting vinyl chloride on special E‐VA types. Graft copolymerisation by the suspension method allows the synthesis of E‐VA/PVC systems in all ratios (up to 80% E‐VA); these polymers are compatible over the whole range in contrast to the blends.Studies on the grafting efficiency of some monomers show that vinyl chloride can be grafted readily on E‐VA.The grafting process is performed on a technical scale to give PVC types with E‐VA contents up to 50%. Products with 6–8% E‐VA should be classified as impact‐modified suspension PVC. Flexible types (40–60% E‐VA) have properties of flexible PVC with the plasticiser chemically incorporated, but may also be blended with unmodified PVC to give impact‐improved formulations.The properties of the elasticised PVC (8% E‐VA) mainly depend on the vinyl acetate (V‐OAc) content of the E‐VA and its molecular weight. Levapren® 450 P (45% V‐OAc; mol. wt. ∼ 100,000), a solution process copolymer, has good elasticising efficiency in blends and graft copolymers with PVC.PVC/E‐VA products may be processed with or without addition of uncombined PVC into rigid or flexible PVC by the usual methods of PVC technology, e.g. extrusion, injection moulding, blow‐moulding and calendering.Competitive modifiers, such as acrylonitrile‐butadiene‐styrene copolymers, methacrylate‐butadiene‐styrene copolymers, acrylates or chlorinated polyethylene, are compared with E‐VA. Levapren® 450 P shows high efficiency as an impact modifier even in low concentration, giving good processability and ageing behaviour. Glass‐clear high‐impact PVC cannot be obtained by E‐VA modification.Some electron microscopy studies to characterise the distribution of E‐VA in the resin phase (PVC) are described; these showed the presence of a two‐phase system.