question: Abstract A murine model to study enteritis induced by bovine (BRV) and murine rotavirus (MRV) has been developed. The course of infection was determined by clinical symptoms of diarrhea and virus isolation as well as histopathological, immunohistochemical, and electron microscopic methods. Both isolates were able to replicate and produce clinical symptoms in neonatal mice. Rotavirus-free neonates were orally inoculated with MRV or BRV and observed over a 192-hr postinoculation (HPI) period. Following infection with 104 PFU of virus, diarrhea and maximal intestinal dysfunction, as measured by xylose absorption, did not occur until beyond 20 hr postinfection even though maximal virus production occurred at 10–15 HPI. Immunohistochemically and by electron microscopy we were able to demonstrate viral antigen and virus particles in the enterocytes of villous tips at 5–8 HPI. The appearance of diarrheal symptoms was dependent on the virus dose and the type of virus isolate inoculated. The disease could be induced with doses as low as 1 × 102 PFU/mouse of BRV and 1 × 101 PFU/mouse of MRV. On the basis of these results, MRV was found to be more virulent than BRV in this model. The model should prove useful for studies designed to assess rotavirus virulence genes and for vaccine protection studies. This work emphasizes the need for early sample collection for critical evaluation of any vaccine or antiviral agent using this model.