Commercial broiler hens were raised from hatch to 42 days of age with 10, 15 and 20 birds per m2 in pens with or without the availability of horizontal perches to examine the effects of the housing on the immune status of the birds. The immune parameters assessed were lymphoid organ weights, antibody response to SRBC in the last 10 days of growth, heterophil:lymphocyte ratios at 32 and 42 days of age, and lymphocyte blastogenesis of peripheral blood lymphocytes collected at 32 and 42 days of age. As bird density increased, bursa weight and bursa/body weight ratios decreased. The bursa weights and bursa/body weight index were also significantly decreased by the addition of perches to the environment. No other significant effects were observed for the flock performance, morphometric data, or immunological tests between treatments. Conclusions stated that, under the conditions of the study, which tried to simulate commercial conditions, the bursal weight was the best indicator of stress related to housing density. Stress appeared to increase with the addition of perches because the birds used the perches infrequently. Therefore, there may have been a further reduction in the availability of floor space to the birds with the addition of perches.