Non-polio enteroviruses are currently the most common agents of the central nervous system viral infection, and are the major causes especially in patients with aseptic meningitis. The practical problems with enterovirus meningitis revealed from the investigation of our patients are as follows. (1) The triad of symptoms of meningitis (fever, headache, vomiting) were seen only in 50% of the older children affected. The only manifestation of neonates with aseptic meningitis was fever. (2) In more than half of the patients, the cerebrospinal fluid showed polymorphonuclear predominance within 3 days from the onset. (3) The causal viruses were isolated frequently (70%) from the cerebrospinal fluid of the children with aseptic meningitis. (4) The patients more than 1 year of age had no sequela clinically. Among neonates and early infants, transient abnormalities of brain CT findings were seen in 40% and delayed speech in 30%. Their prognosis should be investigated more precisely.