New data are presented for the shear behavior of solutions of polyisobutylene in toluene at 25°C. Five samples (viscosity-average molecular weight range of 105 to 5×106) were studied at shear rates from 1.0 to 3×105 sec−1. Both Couette and capillary viscometers were used in the investigation. The results are correlated by a standard reduced variable plot and compared with earlier data. A method for predicting the viscosity of straight chain polymer solutions from minimal data is discussed.