Investigations of the dynamic properties of several polystyrene solutions in the viscous solvent Aroclor 1248 were made, comparing the lower frequency results obtained with the Birnboim instrument with the higher ones in the ultrasonic range using the torsional crystal of Mason. Both sets of values merge well in the overlapping range of reduced frequencies, giving a considerably larger combined range. The viscosityη1of all the solutions at higher frequencies did not approach that of the solvent but reached a higher asymptotic value, not predicted by theory. This causescot δ(with δ the “loss angle”) to have a maximum at intermediate frequencies and explains former ultrasonic results. The influence of the polydispersity on the dynamic properties is not large for the loss modulusG″,but is much larger, as theoretically predicted, for the storage modulusG′.