To investigate the clinical character of an outbreak of aseptic meningitis in Iwamizawa 1997 caused by echovirus 30, and to investigate the spreading of the outbreak, we analyzed clinical character of 75 hospitalized patients in our hospital, and mapped the patients' distribution in Iwamizawa City each week. We detected in our hospital an epidemic outbreak of acute enteroviral meningitis caused by echovirus type 30 in Iwamizawa, from September to December, 1997. Regarding the patients, there was little prevalence in males, with an average age of 6 years and a range of 0 to 13 years of age. The most constant symptoms were three major one such as headache (90%), fever up (89%), vomiting/nausea (87%), sometimes sorethroat (30%) and abdominal pain (15%). One case had a febrile convulsion temporally, and two cases had acute meningoencephalopathy and- encephalitis. In the cereblospinal fluid (CSF), we found no predominance of mononuclear cell (MNC) (58%) in the differential cell count. The mean of the peak of CSF cell counts was 654/3. White blood cell (WBC) was 8940/microliters, and CRP 1.4 mg/dl. None of them was detected in the bacterial culture of the CSF. Viral cultures were performed on CSF in 26 cases. Echovirus type 30 was isolated in 4 cases of hospitalized patients, and in one case with meningismus without pleocytosis. The beginning of the outbreak was observed in two kindergarten and one elementary school side by side. The peak of the whole outbreak was detected in the 3rd to 6th week, however the school spreading peak was detected in the 3rd and 4th week, and spreading was going in the whole city.