An epidemic of encephalitis occurred in the eastern, paddy growing districts of Haryana state between July and November 1990. One hundred and eighty-two patients with encephalitis were admitted to different hospitals in Haryana and 118 of them expired (mortality rate 64.8%); 88% of the patients were children. The male to female ratio was 2. 3. 1. IgM class of antibodies to Japanese Encephalitis (JE) Virus could be demonstrated in the CSF and/or sera of 3 surviving and 2 fatal patients of the 19 patients studied. This is the first detailed report on an epidemic of encephalitis in North-Western part of India. Serologically proven cases of JE are being reported, for the first time, from this region.