"The students were expelled on charges of adopting unfair means. Nearly 100 parents or guardians were arrested for abetment," an official of Bihar School Examination Board (BSEB) said.
According to board officials, the students were caught cheating on the first day of the exam Wednesday.
Some reports said even teachers deployed at exam centres and policemen were seen helping students cheat.
According to the board, over 1.3 million students across Bihar appeared for the Class 10 exams.
The BSEB, which conducts the examinations, said it has made elaborate arrangements for peaceful and fair exams.
But there were reports of widespread cheating from Shekhpura, Muzaffarpur, Darbhanga, Gaya, Patna, Jehanabad and Bhagalpur.