Vibrational Raman spectroscopy was employed successfully for the simultaneous quantitative determination of the cubic, tetragonal and monoclinic phases of partially stabilized zirconia. Pressed pellets with known composition were prepared and used as standard mixtures. From the standard pellets, a calibration curve was obtained which was found to be a straight line if (/(640) - 0.47 /(260))//(177) is plotted against the inverse monoclinic molar fraction. /(260), /(177) are the Raman intensities for the tetragonal and monoclinic peaks at 260 and 177 cm(-1) respectively, and were calculated by subtracting the "background". In contrast, /(640) represents the intensity for the 640 cm(-1) band, which is attributed to all three phases, and was measured including the "background".