1. The effect of stocking density on welfare traits of turkeys was studied in 2 experiments. In each experiment 2,633 sexed BUT turkey poults were assigned to 3 rooms, 135 m2 with 1 treatment per room. Because of the large flock size (675,878 and 1080 birds in T1, T2 and T3 respectively) treatments were not replicated 2. Floor space allowances varied according to treatment; for the males: 24 dm2, 18.5 dm2 and 15 dm2 until week 12 and 40 dm2, 31 dm2 and 25 dm2 from week 12; for the females: 16 dm2, 12.3 dm2 and 10 dm2. 2. The scan sampling method in experiment 1 and the focal sampling method in experiment 2 were used to record behaviour at week 6, 9, 12 (males and females), and 16 (males). Birds' ethogram was divided into 7 mutually exclusive behaviours: standing/walking, resting, feeding, drinking, pecking at the environment, pecking at another bird, and preening. Position changes in the pen and the frequency of disturbances of resting birds by other birds were recorded in experiment 2. 3. Gait was assessed at week 12 (females) and week 16 (males). Prevalence of lesions, breast (males), hip and foot (males and females), were recorded at slaughter. Birds were weighed at week 12 (males and females) and week 16 (males). 4. Stocking density had little influence on behaviour except on the frequency of disturbances of resting birds by other birds, which tended to be more frequent at the highest density. 5. Gait deteriorated as stocking density increased. Hip and foot lesions were more frequent at the highest density. Bodyweight decreased significantly with decreasing floor space. 6. The results suggest that turkey welfare was poorer at the highest density than at the 2 lower stocking densities.