Height profiles of atmospheric water vapor obtained using a multiple-wavelength Raman lidar are examined. The water vapor profiles exhibit vertical structure with scales on the order of the resolution of the lidar (75 m). To determine whether such structure is atmospheric in origin, measurements obtained simultaneously in a common volume at two independent wavelengths were compared. Correlation of the gradients of the water vapor profiles obtained from these two wavelengths yielded an average correlation factor of 0.88. It was observed that for the given meteorological conditions, the vertical structure decorrelated with a time constant of approximately three hours. ¿ American Geophysical Union 1994