Population densities of red and roe deer were estimated in 20 conifer plantations throughout central and northern Scotland. Ten forests were selected on the basis of culling records that were considered likely to cover the range of possible densities. Ten further forests were selected at random to investigate the relationship between red and roe deer densities. Density assessment was by standing-crop dung-group counts, on 1.5 x 100 m transects. Dung decay rates were estimated in four areas and used to convert the values to deer densities. Red deer densities were estimated to range from 0.3-35 km−2; roe deer densities ranged from 0.5-25 km−2. Preferences for different structural habitats within individual forests (i.e. blocks with different age classes of tree) were inferred from dung densities. Red deer preferred unplanted ground, open-thicket, and prethicket; roe deer likewise preferred prethicket (highly) and open-thicket. Both species avoided closed-canopy habitats. Red and roe deer densities were negatively correlated and the relationship was significant when the data were log transformed (P < 0.05).