Densities, viscosities, and refractive indices for binary systems containing mixtures of poly(ethylene glycols) at the same number-average molecular mass (M-n approximate to 300) but different polydispersities (molecular mass distribution between 1.15 and 1.98) with dimethyl carbonate or diethyl carbonate were determined at 313.15 K and at atmospheric pressure. The measurements were carried out over the whole range of composition, using a vibrating-tube density meter, Ubbelohde viscometers with a Schott-Gerate AVS 310 unit, and an Abbe refractometer. Densities, viscosities, and refractive indices were used to compute the excess volumes, V-E, viscosity deviations, Deltaeta, and deviations in molar refraction, DeltaR. Results were fitted to the Redlich-Kister polynomial, and the adjustable parameters were obtained using least-squares methods. The viscosity dependence on temperature was investigated between (309.15 and 327.15) K for some solutions in a restricted composition range. A qualitative discussion on these quantities in terms of molecular interactions is reported.