Until recently, echovirus 13 has been a very rare cause of aseptic meningitis. We investigated an outbreak of echovirus 13 in central Israel during the summer of 2000 using a prospective case control study and a retrospective study. Echovirus 13 was isolated from 79 cerebrospinal fluid (CSF) specimens from different medical centres in central Israel. Patients' ages ranged from 10 days to 41 years (95% <15 years, M/F ratio 62/38). A total of 128 patients with clinical aseptic meningitis were admitted to the Department of Pediatrics during the outbreak (aged 10 days to 18 years, mean 5·4 years), and 58 CSF samples were processed for viral cultures. Thirty of them did not grow any virus, 26 samples yielded echovirus 13, and 2 samples echovirus 7. The clinical features of patients with echovirus 13 in the CSF were similar to those in whom no virus was isolated or those infected with other enteroviral strains except for higher rate of fever on admission, and prolonged time with fever following the diagnosis in the echovirus 13 patients. CSF cell count varied from 4 to 2333 cells\mm3 with polymorphonuclears (PMN) predominant in >90% of our patients. In a case–control study there was no significant difference between patients and matched controls with regard to parameters such as: day care attendance, recreation in summer camp, swimming pools and at the beach, and consumption of tap water. All the patients in our series recovered fully with no neurological abnormalities. The illness caused by echovirus 13 was benign and involved mainly patients younger than 15 year of age. Several features that characterized this outbreak include relatively high WBC in the blood and a prominent CSF PMN response.