The performance of a live marker vaccine for bovine herpesvirus type 1 (bhv-1) was studied in the field in three European Union countries with different farming conditions. The progress in the eradication of the virus was followed in a large herd in Germany and one in Italy, and a major serological survey involving 147 farms was conducted in Hungary. Commercial batches of the same vaccine were used in all three studies. The herds were vaccinated according to agreed protocols and the animals' bhv-1 antibody status was determined at local institutes by using commercial glycoprotein B (gB)- and glycoprotein E (gE)-elisas. In all three studies, the seroprevalence of bhv-1 gE decreased progressively. Given the starting conditions and the long duration of the studies, reactivation events and virus circulation would have been more likely to have occurred if the herds had not been vaccinated.