We report new observations of stationary planetary waves in the Southern Hemisphere of Mars by Mars Global Surveyor (MGS). We focus on a period during midwinter (Ls = 134¿--160¿) when independent observations were acquired by two techniques. Radio occultation experiments sounded the atmosphere at essentially fixed latitude (~68¿S) and local time (~1030), yielding profiles of geopotential and temperature between the surface and the 9 Pa pressure level. Observations by the Thermal Emission Spectrometer (TES) included systematic limb sounding at nine discrete latitudes and two local times (~0200 and ~1500), yielding temperature profiles at pressures of 1--100 Pa. We supplemented these data with a simulation by a Mars general circulation model (MGCM), which provides an accurate synthesis of the observations. These stationary planetary waves have significant amplitudes at zonal wave numbers s = 1 and 2. The s = 1 component propagates vertically, as reflected by a westward tilt with increasing height in the geopotential and temperature fields and a net poleward eddy heat flux. The peak amplitude at s = 1 is ~1 km in geopotential height and ~7 K in temperature. The geopotential field of the s = 2 component is barotropic in character, which results through hydrostatic balance in a distinctive temperature field. The peak amplitude at s = 2 is ~700 m in geopotential height and 4--6 K in temperature.