Central European tick-borne encephalitis is mainly found in Central European countries and Austria where hundreds of cases are reported each year. Apart from 2 cases diagnosed in Alsace in 1968 and 1970 respectively, this disease was hitherto unknown in France. We report 8 new cases observed in Alsace between 1985 and 1990. Clinical presentation in these 10 patients was a pure meningitis syndrome in 4 cases and meningo-encephalitis in 6 cases, very severe in 3 of them. All patients recovered rapidly, and only 3 have slight sequelae. In a seroprevalence survey conducted in 1989 among 619 professional foresters of Eastern France, 8% were found to be seropositive, which suggests that the disease is often unrecognized. A study of the large series published in Austria and in other Central European countries has shown that the prognosis of tick-borne encephalitis is not always as favourable as it was in the Alsatian cases: severe sequelae or death occur in 1 to 2% of the patients. The need for a better detection of the disease and for vaccination of the subjects at risk must be emphasized.