Densities and excess molar volumes of the following eight n-alkane binary liquid systems were measured over the entire composition range at 293.15 and 298.15 K and at atmospheric pressure : n-octane-n-undecane, n-octane-n-tridecane, n-octane-n-pentadecane, n-decane-n-pentadecane, n-undecane-n-pentadecane, n-tridecane-n-pentadacane, n-decane-n-tridecane and n-undecane-n-tridecane. All the excess molar volume values are negative. In general, it was found that the absolute values of the excess molar volumes of mixing increased with an increase in the difference of the number of carbon atoms of the components forming the system.