This paper reports the investigation of risk factors for bovine herpesvirus-1-seropositivity, based on a cluster-sample survey of the Belgian cattle population. This serosurvey was carried out in 1998 in 309 randomly selected unvaccinated herds of all types (dairy, mixed and beef) were all bovids (N = 11,284) were sampled. Older and male cattle had higher seroprevalence. Origin (homebred or purchased) and herd size interacted; for smaller herds (50 cattle on the premises), purchase status and larger herd size were risk factors, whereas these effects were not observed for larger herds. ; The BHV-1 survey was supported by the Fund for Animal Health and Production, Federal Public Service Health, Food Chain Safety and Environment, Belgium.