The NCAR thermospheric general circulation model (TGCM) for the Earth's thermosphere has been modified to examine the three-dimensional structure and circulation of the upper mesosphere and thermosphere of Mars (MTGCM). The computational framework and major processes unique to a CO2 thermosphere are similar to those utilized in a recent Venus TGCM. Mean orbital, seasonal, and solar conditions are specified. An Equinox version of the MTGCM is used to predict the Mars solar driven global circulation and structure for a non-dusty (quiet) lower atmosphere at the time of arrival of the two Phobos spacecraft. ¿ American Geophysical Union 1988