The congenital rubella syndrome provides the best documentation in humans that a viral infection is associated with the subsequent development of insulin-dependent diabetes mellitus. We have developed an animal model in neonatal golden Syrian hamsters infected with rubella virus passaged in beta-cells that closely parallels the diabetes observed with congenital rubella. The hamsters develop hyperglycemia and hypoinsulinemia, which are sustained throughout the 15-wk study period. A mononuclear infiltration of the islets, isolation of rubella virus from whole pancreas, the presence of viral antigen in beta-cells by immunofluorescent localization, and cytoplasmic islet cell antibodies (40%) are demonstrated. These data suggest that an autoimmune process and diabetes develop after rubella virus infection in neonatal hamsters. This model may uncover the precise mechanism by which rubella virus induces similar disease in humans.