Muzaffarpur civil surgeon Gayan Bhushan said five more children succumbed to encephalitis since Friday in state hospitals.
"So far, 23 children died of encephalitis this year," he said.
Over half a dozen children were warded in government hospitals and in private nursing homes in Muzaffarpur, about 70 km from here.
Bhushan also informed, 77 encephalitis cases have been reported across the state.
The symptoms of this mosquito-borne disease include high fever, irritation and swelling in the brain.
Bihar Health Minister Ashwani Kumar Choubey blamed the deaths on the sudden rise in mercury in the last few days, following rains in north Bihar, and humid weather.
Last year, the disease killed nearly 240 children in Muzaffarpur and Gaya districts.