Background.Before 2001, echovirus 13 accounted for only 65 of ∼45 000 reported enteroviral isolates in the United States. During spring 2001, several outbreaks of echovirus 13 meningitis occurred, primarily affecting children. We investigated a large outbreak in Shelby County, TN, to determine the characteristics and clinical manifestations of echovirus 13 meningitis.Methods.We identified cases of aseptic meningitis at a children’s hospital from April through August 2001 by reviewing discharge records. For patients with laboratory-confirmed echovirus 13 meningitis, we reviewed charts and interviewed parents.Results.We identified 303 hospitalizations caused by aseptic meningitis at the children’s hospital from April through August. Hospitalizations peaked in May. Twenty-six percent of hospitalized patients were infants age <4 months; 63% were male. Hospitalization rates were 3 times greater among black children than among white children (140vs.47 per 100 000). Echovirus 13 was isolated from specimens from 37 (80%) of 46 patients with positive viral cultures. Of those with laboratory-confirmed echovirus 13, 35 (95%) had fever, 26 (70%) had vomiting, 20 (54%) had headache, 16 (43%) had stiff neck and 16 (43%) had irritability. No sequelae or deaths were identified.Conclusions.Echovirus 13 emerged as a predominant strain of enterovirus associated with aseptic meningitis in the United States in 2001. In this outbreak echovirus 13 meningitis appeared to be clinically indistinguishable from aseptic meningitis caused by other enteroviruses.