Important rheological properties of viscoelastic fluids can be obtained by studying continuous flow through a channel approximating infinite parallel plates. This flat plate rheometer eliminates or reduces some problems of conventional ones and extends the region of useful measurements to high shear rates. Four pressure transducers are flush mounted on the top plate to measure the normal stressT22.From these measurements the shear stress can also be obtained. The normal stress in the direction of flow(T11)is obtained from the measurement of the impact of the exit stream. A Weissenberg rheogoniometer (WRG) is used to measure the shear stress and the primary normal stress difference(N1=T11−T22).Data are presented for polyethylene oxide(M̄w=4×106)solutions of 0.25%, 0.9%, 2.0%, and 3.0% in water. Newtonian fluids were used to test and compare the apparatus. Fluid viscosities from 0.01 to 6000 poise and normal stresses from 100 to450,000 dynes/cm2were determined for shear rates from 0.03 to130,000 sec−1.The rotational geometry of the WRG limits its use to shear rates under102–103 sec−1.Further, the precision of normal stress measurement with the parallel plates is better than obtained with the WRG. The shear stress values obtained with the plates are of equivalent precision and higher accuracy. Normal stress dependence upon shear rate is fit by the molecular dumbbell model of Bird et al. over a wide range of conditions. In the upper region the model predicts a slope of 2/3 and0.66±0.03is obtained by regression analysis of the data. In the lower region a slope of 2 is predicted and2.08±0.37obtained. Extrapolation ofT11andT22data using this model allowsN1to be obtained at shear rates far higher than with the WRG. The magnitude of the ratioT22/T11decreases as Polyox concentration increases and the fluid becomes more elastic. The complete state of stress is determined for all Polyox solutions, and pressures at the exit surface and exit centerline are found to contribute substantially to the total stress tensor.