The densities and viscosities of concentrated aqueous solutions of polyethylene glycol (10-50 mass %) have been measured. The polyethylene glycol samples had average molecular masses of 8000,3350, and 1000. The values of the density from 277 to 298 K show a linear variation with the polyethylene glycol concentration and differ, at most, by 10.07 % from those of pure water at the same temperature. In order to estimate the values of dynamic viscosity, an equation is proposed which takes into account the influence of the polyethylene glycol concentration and the temperature in the range 277-313 K. The viscosity of mixtures of polyethylene glycol + magnesium sulfate + water were also studied. A linear relationship exists between the viscosities of the aqueous solutions of polyethylene glycol and the concentration of magnesium sulfate.