The immunity development, the intensity of the humoral and cellular immune response, efficacy of protection and the ability to overwhelm colostrum-derived specific antibody was stududied after the intradermal (ID) vaccination in piglets. The ability of piglets to develop immunity was measured at 3, 7, 14 and 28 days. Full immune-competence was confirmed in piglets aged 28 days. Groups of younger piglets, vaccinated at 3, 7 and 14 days, showed a measurable response, agedependency was corresponding with the maturation of the immune organs and cells. Immunity development was researched further in piglets with colostrum-derived antibodies compared with piglets without colostrum-derived antibodies. Piglets vaccinated ID after weaning also exhibited fully comparable results to IM administration. The serology results were confirmed through challenge infection of Actinobacillus pleuropneumoniae. Results of the trial confirmed that ID vaccination provoked the same, or even stronger, protection in comparison to IM vaccinated animals. The different quantities of antigen in ID vaccines resulted in not proportional levels of protection.