Antibody titers after vaccination against Infectious Bronchitis Virus (IBV), Newcastle Disease Virus (NDV) and after natural infection with Campylobacter were analyzed in five trials with Lohmann Silver laying hens kept in two different housing systems. In these studies it could be demonstrated that antibodies against IBV and Campylobacter were in 4 out of 5 respectively in 2 out of 5 trials significantly higher in hens housed in an aviary system compared to those kept in furnished cages. The opposite trend was observed for antibodies against NDV which were on average significantly higher in cages. The mean mortality rate was slightly higher in hens kept in the aviary system compared to the cage system.