This experiment was carried out to investigate the effects of the laying hens on the immune response against bovine serum albumin(BSA) in egg yolk. Total 45 laying hens were divided into three groups according to breeds (White Leghorn, ISA Brown, Native hen). They were fed the experimental diet for 12 weeks. Immune response were examind in egg yolk from three groups of hens injected with BSA. The results obtained from this work were summaried as follows : 1. The weight of egg yolk and the percentage of hen-day production in the ISA Brown hens are greater than those in the Native hens and the White Leghons. 2. IgY concentrations in eggs from hens immunized with BSA were not different among the breeds laying hens. 3. The anti-BSA antibody activities determined by enzyme linked immunosorbent assay (ELISA) in the egg yolk were similar between the White-Leghorn and ISA Brown hens, but Native hens tended to decrease in 20∼50 days respectively. Therefore, the weight of egg yolk and the percentage of hen-day production in the ISA Brown hens are greater than those in the Native hens and the White Leghons will be as important factors for an efficient production of IgY.