We report a series of atmospheric aerosol backscatter measurements at two widely spaced CO(2) laser wavelengths: 9.25 and 10.6 microm. Comparisons are made beween backscatter coefficient profiles at these two wavelengths up to 20-km altitude. Measurements such as those reported here can be used to assess the feasibility of coherent CO(2) lidar for wind measurements, and they also provide a partial test of backscatter model predictions.