Adult cases of viral meningitis caused by echovirus type 13 (E13) were studied. 
E13 was isolated from 8 of 11 adult patients (73%) with viral meningitis between 
April and September 2002 in Fukui Prefecture. The mean age was 27.4 +/- 6.4 
years (4 males and 4 females). The disease was prevalent among adults, 
especially younger adults as well as children. The symptoms and signs were as 
follows; headache (100%), fever (100%), nausea and/or vomiting (88%), Kernig's 
sign (88%), and increased deep tendon reflexes (50%). The average cell counts in 
cerebrospinal fluid (CSF) were 118 +/- 111/mm3. Of the 2 patients, polynuclear 
cells were dominant during the early phase of the disease. The prognosis was 
good. Since May 2002, the number of patients with viral meningitis caused by E13 
has rapidly increased. Most of the reported patients were children. We should 
consider the possibility of E13 infection as a cause of adult viral meningitis.