An echovirus 11 outbreak occurred among neonates in an obstetric clinic in November 2003. Thirteen neonates were transferred to our medical center, and all were found to have echovirus 11 infection. Viral studies were performed for 32 other infants born in the clinic during the same period, including 30 asymptomatic neonates and 2 febrile infants transferred to another hospital. Two of the asymptomatic infants had echovirus 11 isolated from rectal swabs. The first patient transferred to our medical center developed extensive hemorrhage and died 6 days later. Three family members of this infant were also proved to have echovirus 11 infections. One other infant had a fulminant course and had residual hepatic impairment. The other infants had no complications. Viral studies in the 24 nursery staff were all negative. This outbreak shows how a neonatal enterovirus outbreak can occur in a nursery, starting from an infected infant in the incubation period. Early recognition and prompt management of an outbreak is important to prevent further spread of the infection.