We investigated experimental transmission of duck hepatitis B virus to its original host, the domestic Pekin duck, and to three other avian species. Intramuscular injection of a standard inoculum of duck hepatitis B virus into 2- to 5-day-old Pekin ducklings hatched from a duck hepatitis B virus-free flock resulted in viremia in 100% of 107 animals, indicating that duck hepatitis B virus infection of young progeny of a defined duck hepatitis B virus-free flock occurs reproducibly. When the same inoculum was injected into chicks and Muscovy ducklings of the same age, no evidence of viral infection was detectable. In contrast, hatchlings of two domestic breeds of geese were readily infected by duck hepatitis B virus, developing viremia at a slower rate than Pekin ducklings, but a higher average titer of viremia 4 weeks or more after injection. Neither the pattern of restriction enzyme sites in the viral DNA nor the susceptibility of ducklings to the virus were detectably altered after passage in geese. As in duck hepatitis B virus-infected young ducklings, most of the experimentally infected goslings appeared to be persistently infected and those eventually laying eggs transmitted virus to the progeny. While ducklings exhibited a fairly uniform inflammatory response to the virus, duck hepatitis B virus inoculation of the goslings resulted in both inflammation and an altered hepatocellular morphology not seen in uninjected controls. The host range of duck hepatitis B virus appears to be limited to the primary host and a close taxonomic relative, similar to other members of the hepadnavirus family, hepatitis B virus and ground squirrel hepatitis virus.