A number of examples of the use of a detailed Monte Carlo (MC) simulation program for EDXRF spectrometers is discussed. The MC code is employed to predict the complete spectral response of a polychromatic EDXRF spectrometer using different excitation conditions. With respect to quantification of steel samples in which sign*cant enhancement and self-absorption occur, the usefulness of the code in simulating spectra corresponding to calibration standards is demonstrated. An extension of the program that deals with simulating the interaction of polarized radiation with matter is used to estimate the analytical qualities of currently operating and future monoand polychromatic synchrotron radiation XRF spectrometers.