Using ten years of solar radiation data, the surface albedo of twenty-four sites in the Kingdom of Saudi Arabia was calculated, and annual, seasonal, and geographical variations were investigated. The selected sites encompass a wide range of atmospheric conditions. The mean annual albedo values range from 0.15 to 0.54, and show high variability between different sites and even at individual sites. The differences between the maximum and minimum albedo range from 0.02 to 0.44. The average albedo over the entire kingdom is 0.31 +/- 0.05. Seasonal investigations revealed that the lowest albedo values occurred during the summer and the highest in the winter. In examining the variations of the calculated albedo with the altitude, sites were divided into three groups: low altitude (0-500 in), middle altitude (500-1000 m), and high mountain sites (higher than 1000 in); the mean albedo values for each category are 0.32, 0.31, and 0.28. respectively. In studying the effects of latitude on albedo values, the sites were also divided into three groups: low latitudes (15-20), middle latitudes (20-25), and high latitudes (> 25), for which the mean monthly albedo values are 0.25, 0.30, and 0.31, respectively. (c) 2008 Elsevier Ltd. All rights reserved.