Regional seismograms of intermediate-depth earthquakes (50≤H≤80 km) that occur below the Central Mexican Plateau show a phase which, at epicentral distances of 150 to 450 km, arrives about 15 to 20 sec after the P wave and 5 to 12 sec before the S wave. This phase was previously interpreted as a seismic wave refracted from a dipping interface below the source, thus apparently providing direct evidence of the structural location of the subducted Cocos plate below M¿xico. The phase was called the plate wave. Recent intermediate-depth events have given rise to better quality data recorded by some newly-installed broadband seismographs. An analysis of these and previous data strongly suggests that the phase is an S-to-P converted phase at the free surface and, therefore, provides no information regarding the subducted plate. ¿American Geophysical Union 1995