A Raman Lidar system based on a pulsed Nd: YAG laser has been employed for regular monitoring of the columnar water vapour mixing ratio at the Andalusian Centre for Environmental Studies (CEAMA) (37.16° N, 3.58° W, 680 m a.s.l.), at Granada (southeast of the Iberian Peninsula). This methodology is employed continuously for the first time on the Iberian Peninsula. The Raman Lidar water vapour channel has been calibrated by comparison with simultaneous co-located radio-sounding during a field campaign at El Arenosillo, Huelva, Spain (37.11° N, 6.73° W, 0 m a.s.l.) at the end of June 2006. Since September 2005, systematic water vapour Lidar measurements have been performed. Water vapour Raman Lidar measurements taken at night time over 1 year (from September 2005 to August 2006) have been studied and compared in terms of precipitable water with respect to real radio-sounding data from the two closest radio-sounding stations. In addition, the seasonal variability of the water vapour mixing ratio has been analysed.