Specification of a method for determining the apparent viscosity, at high shear, of polyvinylchloride pastes prepared from polyvinylchloride polymers and plasticizers. It applies in particular to "standard pastes" according ISO 4612. Placing of a sample in a Severs rheometer and setting of the jacket to a defined temperature. Measurement of the flow rate of the paste through a calibrated die at different pressures. Calculation of the shear rate and apparent viscosity for each flow rate corresponding to each of the pressures applied.