We present measurements of the latitudinal variation of nighttime O3 and H2O in the mesosphere and (for O3) lower thermosphere obtained with the Millimeter-wave Atmospheric Sounder (MAS) instrument during the ATLAS 2 mission (8--15 April 1993). These are the first such measurements that have ever been reported. They indicate an O3 mixing ratio minimum at mid-latitudes in the upper mesosphere, with maxima in the tropics and at high latitudes. The H2O retrievals indicate H2O mixing ratios decreasing toward the poles in both hemispheres in the upper mesosphere. We also present measurements of the diurnal variation of O3 at southern mid-latitudes, at higher vertical resolution than has ever been reported previously. The results are generally consistent with previous measurements and modeling studies. ¿ American Geophysical Union 1996