Sera collected from European wild boar (Sus scrofa) shot in Eastern Germany between January 1991 and December 1994 were tested for antibodies to pseudorabies virus (PRV). Of 3,143 sera tested, 281 (8.9%) and 13 (0.4%) were positive and suspect in an enzyme-linked immunosorbent assay (ELISA), respectively. The specificity of the reactions was confirmed by detection of neutralizing antibodies in 220 sera (74.8%) and by immunoblotting. Analysis of host age and sex of the animals, temporal and spatial factors showed significantly higher seroprevalences in older animals than in younger individuals, but no differences between males and females. Pseudorabies virus infections have been endemic in this wild boar population for several years and the extreme eastern part of the study area had significantly higher seroprevalences (< or = 22%) than other areas. In the area covered by this study, pseudorabies virus was eradicated in the domestic animal populations in 1985. Thus, the infections in the wild boar population appear to be endemic and persist completely separately and without affecting the domestic pig population.