Eid was celebrated peacefully in Bihar on Friday with no reports of violence, police said.
Millions of Muslims offered prayers in mosques across the state followed by sacrifice of animals, mostly goats, in memory of Prophet Ibrahim.
In Patna, thousands of Muslims prayed at Gandhi Maidan and at various mosques.
Apprehending trouble by anti-socials before the upcoming Bihar assembly polls, additional security forces were deployed in sensitive places in the state to prevent any untoward incident, a police official said.
Bihar Chief Minister Nitish Kumar directed officials to keep round-the-clock vigil.