In recent years, many mumps outbreaks have occurred in vaccinated populations worldwide. The reasons for these outbreaks are not clear. Animal models are needed to investigate the causes of outbreaks and to understand the pathogenesis of mumps virus (MuV). In this study, we have examined the infection of three animal models with an isolate of mumps virus from a recent outbreak (MuV-IA). We have found that while both ferrets and mice generated humoral and cellular immune responses to MuV-IA infection, no obvious signs of illness were observed in these animals; rhesus macaques were the most susceptible to MuV-IA infection. Infection of rhesus macaques via both intranasal and intratracheal routes with MuV-IA led to the typical clinical signs of mumps 2 weeks to 4 weeks postinfection. However, none of the infected macaques showed any fever or neurologic signs during the experimental period. Mumps viral antigen was detected in parotid glands by immunohistochemistry (IHC). Rhesus macaques represent the best animal model for the study of mumps virus pathogenesis.