Comparisons are made of L band and X band SAR images with in situ measurements of surface currents and surface wave spectral perturbations for two of the Joint Canada-U.S. Ocean Wave Investigation Project internal wave data sets. Predicted and observed perturbations show agreement to within approximately a factor of 2 for L bands, while the agreement at X band is muich less satisfactory. Comparison of predicted microwave backscatter at X band with near-surface radar measurements indicates large discrepancies even when surface tilt and specular reflection effects are included in the model. Synthetic aperture radar (SAR) X band modulations compare favorably with near-surface radar measurements for range-traveling internal waves, but for other directions, the SAR modulations are smaller than the near-surface radar measurements. Simultaneous X and L band SAR images show comparable internal wave modulation. ¿ American Geophysical Union 1988