We present the first results of the operation of a Rayleigh lidar from the Arecibo Observatory. The device consists of an injection seeded, frequency doubled, Nd:YAG laser coupled with a single etalon, Fabry-Perot interferometer in the receiver, the combination of which permits Doppler observations of the backscattered spectral emission from the mesosphere. The measured winds from our initial experiments show a great deal of variability on time scales that appear to be less than the hour it takes to measure a wind profile with the present system. ¿ American Geophysical Union 1991