Aujeszky’s disease virus (ADV) is an alphaherpesvirus that causes Aujeszky’s disease (AD) in pigs and is present worldwide. Some countries are free from AD, while others, like Poland, just starting eradication program. The aim of the study was the determination of passive protection’s duration, transferred from sows to piglets after using attenuated vaccine, and definition the optimal time for active immunization of piglets derived from immune sows. Several protocols of vaccination of piglets against AD were evaluated with regard to development of humoral immunity in the presence of maternal antibodies. Specific antibodies to the gB and gE of ADV were determined using commercially available ELISA kits. Two weeks after the second vaccination there were no significant differences between sows in the level of anti-gB antibodies in serum and all sows developed humoral immunity. Maternally derived antibodies in the sera of piglets born from vaccinated sows were above level considered to be positive until about 11 weeks of live. The immune response, based on ELISA S/N ratio, was the highest in group vaccinated at 10 and 14 weeks of age. In this age the animals were still protected by passive immunity, but simultaneously were able to develop an active humoral response. It could be also concluded, that the high level of maternally-derived antibodies may successfully blocked developmental of active humoral immunity.