A comparative evaluation of vaccination methods with glycoproteins for the induction of immune responses and protection of the pig against Aujeszky's disease virus (ADV) was performed. Different vaccination routes (intradermal (I.D.) versus intramuscular (I.M.)), inoculation sites (the neck versus the back) and number of inoculation points (2 versus 6) per site were compared, Body weight (BW) changes and viral excretion after challenge were compared with virus-neutralizing titers, antigen-specific IgG and IgA responses in serum and virus-specific lymphoproliferative responses in peripheral blood during the immunisation period. According to BW changes better protection was obtained with six-point than two-point I.D. injections. I.D. vaccination in the back at six points gave similar results as I.M. vaccination in the neck but appeared inferior in the reduction of virus excretion, Regarding the immunological parameters, the virus-specific IgA response in serum gave the best indication for protection. It can be concluded that according to BW changes, six-point I.D. immunisation in the back and I.M. immunisation in the neck provided the best protection and that six-point I.D. injections resulted in a better vaccination than two-point I.D. injections. (C) 1997 Elsevier Science B.V.