The diet and breeding density of 19 pairs of Common Buzzard Buteo buteo were studied in relation to indices of lagomorph and vole abundance during June-July 1993 in a range of habitats in southern Scotland. Lagomorphs, voles and birds formed over 70% of the food items analysed from prey remains and pellets collected at nest sites. Indices of prey abundance differed significantly between habitat types. The percentage of lagomorph in Buzzard diet in different localities was significantly correlated with the index of lagomorph abundance; no such correlation was found between the percentage of vole in Buzzard diet and an index of vole abundance. The mean nearest-neighbour distance between Buzzard nests was 1.9 km. There was a significant negative correlation between nearest-neighbour distance and lagomorph abundance. It appears that lagomorphs were the primary prey which influenced the diet and breeding density of Buzzards in the study area.