ABSTRACT The current experiment was conducted to evaluate the effect of stocking density (SD) on the performance and immunity of 1- to 14-d-old broilers. A total of 1836 one-day-old Cobb 500 broilers were housed at four different SD (30, 60, 90 and 120 chicks/m2). Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were estimated on d 2, 5, 8, 11 and 14. Relative lymphoid organ weights, maternal antibody titers against IBV, IBD and NDV, and stress indicators were estimated on d 3, 6, 9 and 12.The results indicated that age significantly (p<0.001) affected the performance and immunity of broiler chicks. Stocking density significantly (p<0.001) affected the performance and physiological stress indicators of broiler chicks, but not maternal immunity, relative lymphoid organ weights, or blood glucose levels. A significant interaction between age and density was determined for BWG, FI and FCR, and maternal antibody titers against IBD and NDV. The results also indicated that the effects of SD were age-dependent: as SD increased, worse performance, lighter lymphoid organs, and stronger stress responses were observed as broilers aged. It is concluded that the higher the SD during the first two weeks of life, the worse is the performance as broilers age.