The dead include two children from Maharajganj district, one from Gorakhpur and one from Bihar.
The four patients died at the BRD Medical College Hospital here yesterday, Additional Director, Health, S K Srivastava said.
Seventy-five persons suffering from the disease have been admitted to the hospital during the past two days, he said, adding 171 encephalitis patients are being treated at BRD-MCH at present.
As many as 1,347 encephalitis patients were admitted to BRD-MCH and government hospitals of Gorakhpur and Basti divisions since January this year, of which 275 died.