Repolling began on Saturday morning at 25 polling stations in Bihar's Siwan Lok Sabha constituency, where polling took place in the second phase on April 26.
The repoll was peaceful in the early hours amidst elaborate security arrangements, official sources said.
Rashtriya Janata Dal strongman Mohammad Shahabuddin is pitted against Amar Nath Yadav of the Communist Party of India (ML) here.