Winds and waves measured by the Medium Frequency Radars (MFR) at Saskatoon (52N, 107W), Robsart (49N, 109W), and Sylvan Lake (52N, 114W), and the Fabry-Perot Interferometer (FPI) at Saskatoon are compared. Particular care has been taken to exclude FPI airglow (558 nm, green line) contamination by aurora or scatter from clouds; radar data were selected from high signal-to-noise conditions. Comparisons between the MFR/FPI in seasonal wind climatologies (at a radar height of 98 km) and wind speed ratios and direction-difference histograms for the Saskatoon systems show excellent agreement. Zonal and meridional wind comparisons (scatter plots) also show no significant differences in mean winds between the FPI and MFR. Differences between instantaneous measurements, as seen on 91 individual days, are categorized into four types of events, depending upon FPI/MFR similarities and differences and the dominance of the solar tide. A gravity wave model is then used to demonstrate the effects of waves, with scales from hundreds to several thousand of kilometers, upon such optical and radar systems, each of which has a different inherent spatial averaging. The model is largely successful in explaining the differences between the instantaneous MFR and FPI measurements. The relevance of such comparisons to satellite/ground-based collaborations is briefly discussed. ¿ American Geophysical Union 1996