The current study was carried out to establish whether broiler chickens reared in large pens congregate in specific areas, and where this occurs if it does occur. Lying areas were also researched and two areas were distinguished: one containing drinkers and feeders (DF area) and one that was free of equipment (Free area). Chicken distribution within pens of equal space allowance was examined in the first experiment. In the second experiment, distribution of chickens in pens differing in density was examined. Behaviour of 16 chickens via scan sampling was carried out as was recording of the presence of cutaneous dermatitis and valgus and varus deformities in the second experiment. Results of the study indicated that chickens at the higher density stayed and lay in the Free area. When housed under the low density, they preferred to stay and lie near drinkers and feeders and had limited use of the Free area. Space allowance in the Free area had no influence on behaviours performed in that area. The chickens behaved similarly at both the high and low densities. Rearing density affected the occurrence of foot pad and hock dermatitis but not the occurrence of varus and valgus deformities. The results of the study show that chickens spontaneously limit their physical effort and only rarely went to some parts of the pen when reared at low densities. The results of this study therefore emphasize the need to find situations that could stimulate activities to avoid local densities that may have deleterious effects on health and comfort.