We here propose a method for rapid, high-frequency seismogram calculation that makes use of an algorithm to automatically generate an exhaustive set of seismic phases with an appreciable amplitude on the seismogram. The method uses a hierarchical order of rays and seismic phases generation, taking into account some existence constraints for ray-paths and some physical constraints. To compute synthetic seismograms, the COMRAD code (from the Italian: “COdice Multifase per il RAy-tracing Dinamico”) uses as core a dynamic ray-tracing code. To validate the code, we have computed in a layered medium synthetic seismograms using both COMRAD and a code which computes the complete wavefield by the discrete wavenumber method. The seismograms are compared according to a time-frequency misfit criteria based on the continuous wavelet transform of the signals. Although the number of phases is considerably reduced by the selection criteria, the results shows that the loss in amplitude on the whole seismogram is negligible. Moreover the time for the computing of the synthetics using the COMRAD code (truncating the ray series at the 10^th generation) is 3-4-fold less than that needed for the AXITRA code (up to a frequency of 25 Hz).