The Whitewater Arroyo virus (WWA) is a newly described North American arenavirus. The purpose of this study was to elucidate the biology of this virus in its natural rodent host, Neotoma albigula (white-throated woodrat). Thirteen adult, 7 juvenile, and 8 newborn woodrats each were inoculated subcutaneously with 1,000 cell culture infectious dose50 of the WWA virus prototype strain AV 9310135. All 28 animals became infected (as measured by the recovery of infectious virus and/or seroconversion) and no overt illness was associated with infection. Infection and virus shedding in the adult animals were transient (less than 59 days) whereas virus shedding in animals inoculated at birth persisted through 164 days of age. These results indicate that the duration of WWA virus infection in N. albigula is dependent upon the animal's age at the onset of infection and that neonatal infection can result in chronic (perhaps lifelong) virus shedding.