Abstract. In this work, novel patent pending rectangle orifice die design has been proposed and tested for planar extensional viscosity measurements of extrusion coating LDPE through entrance pressure drop determination on conventional twin bore capillary rheometr. The obtained results have been compared with the corresponding uniaxial extensional viscosity data and different strain hardening level in both viscosities has been identified. It has been suggested that uniaxial and planar extensional viscosity measurements, utilizing novel orifice die design, can be considered as a very useful and simple tool to fulfill basic aims of the applied rheology.