The children complained of uneasiness after the meal at the Dera Baba middle school in Buxar district, about 125 km from here, a district official said.
They were admitted to a government-run primary health centre at Simri and are said to be out of danger.
The official said some children informed the authorities that there was a dead lizard in the meal served to them.
"It may be true or a rumour. I have asked an official to inquire into it and submit a report soon," the official said.
Police collected samples of the meal, he added. Doctors, who examined the children, did not find any sign of poison.
This is the second such incident in less than 10 days in the state.
At least 24 students fell ill July 18 in Vaishali district after eating the mid-day meal at a government school.
Last year, 23 students died after eating a poisonous meal at a primary school in Saran district.
In Bihar, 16 million students get food under the mid-day meal scheme, which is running in 72,000 schools across the state.