Apparent viscosity over a range of106 s−1in shear rate and first normal stress difference functions for dilute drag‐reducing solutions of Separan AP‐30 in distilled water were measured for both freshly prepared and shear‐degraded solutions, for concentrations from 100 to 500 wppm. A nonlinear integral constitutive equation is proposed which accurately represents these data, and the effects of concentration and shear degradation on the properties (e.g., the model parameters) is shown. Shearing has a greater effect on the low shear viscosity of these solutions than it has on the elastic properties, resulting in a greater degree of drag reduction for the sheared than the fresh solutions.