Prominent candidates include Sharad Yadav, Hukum Deo Narain Yadav, Ali Ashraf Fatmi, Kirti Azad, and Pappu Yadav.
As many as 94 candidates are in the fray for the Lok Sabha polls in Madhepura, Jhanjharpur, Madhubani, Darbhanga, Samastipur, Begusarai and Khagaria.
By-poll is being held for the Sahebpur Kamal assembly seat in Begusarai district. Former minister Parveen Amanullah resigned from the seat and joined the Aam Aadmi Party.
More than 11 million people are eligible to vote at 10,157 polling booths.
A total of 58,215 poll officials have been tasked with the job of holding the polls.