Total mass attenuation coefficients of aqueous solutions of urea, having concentrations ranging from 0.06 to 0.22 g/cm3, have been determined by performing transmission experiments in a narrow beam geometry at 662 keV. The sphere transmission method has also been employed for the direct measurement of mass energy absorption coefficients of these solutions by placing a point source of 137Cs inside a spherical shell. Analysis of the experimental data in terms of cross sections and effective atomic numbers is presented.