The Rashtriya Janata Dal (RJD) on Wednesday won the Jehanabad assembly seat bypoll.
The seat had fallen vacant after death of RJD MLA Mundrika Singh Yadav.
RJD had fielded his son Uday Yadav is the seat who beat the JD(U) candidate by over 35,000 votes.
Meanwhile, BJP's Rinky Rani Pandey has won the Bhabhua Assembly seat in Bihar.
The result of the Araria Lok Sabha constituency is also out, RJD's Sarfaraz Alam has won the Araria Lok Sabha seat.
In Bihar, the ruling JD(U)-BJP combine and the opposition RJD-Congress alliance was locked in a battle in Araria Lok seat and the two Assembly constituencies.
According to election office sources, a total of 28 rounds of counting took place for results of Araria Lok Sabha seat bypoll necessitated due to the demise of RJD MP Mohammad Taslimuddin.
Alam, who crossed over from JD(U) to Lalu Prasad's party RJD to contest the bypoll, is son of Taslimuddin.
While Araria recorded 57 per cent voter turnout, Bhabua and Jehanabad Assembly constituencies recorded 54.03 per cent and 50.06 per cent voting in March 11 elections.
Bypoll in Araria Lok Sabha constituency is was a test for the ruling Janata Dal-United-BJP combine in Bihar as well as the opposition Rashtriya Janata Dal-Congress alliance.
There were reports of police resorting to the mild use of force outside the counting centre in Jehanabad as young RJD supporters indulged in boisterous jubilations over the news of their candidate Suday Yadav establishing an unassailable lead over former MLA and JD(U) nominee Abhiram Sharma.