Enterovirus infections occur throughout the year, but in temperate climates infections are strikingly more prevalent in the summer and autumn. About 50~80% of nonpolio enteroviral infections are completely asymptomatic. The fecal-oral route is thought to be the predominant mode of enterovirus transmission, because viral shedding from the gastrointestinal tract is more prolonged than is shedding from the upper respiratory tract. Even symptomatic infections usually produce undifferentiated febrile illnesses lasting a few days, and often accompanied by symptoms of upper respiratory tract. It has been known that the most common cause of aseptic meningitis is enteroviruses, and this type of meningitis demonstrates benign clinical course and the absence of signs of parenchymal brain involvement. We could see many children with meningitis in the summer of 2008. Among 1,922 children with aseptic meningitis from 1 week to 29 weeks of 2008, 882 (49.9%) was 3~6 years old, and 883 (50.1%) was 7~14 years old. Echovirus 30 (60%) and Echovirus 6 (30%) caused large outbreaks throughout South Korea from May to August 2008, which was analyzed by the Division of Enteric and Hepatitis Viruses, National Institute of Health in Seoul, Korea.