| Name of the Candidate | Party Name | Result |
| RAJENDRA KUMAR | Rashtriya Janata Dal | 75203 |
| KRISHNANDAN PASWAN | Bharatiya Janata Party | 64936 |
| VIDYA SAGAR ARYA | Communist Party of India | 2867 |
| AVDHESH RAM | Independent | 2138 |
| VINDESHWARI RAM | Garib Janta Dal (Secular) | 893 |
| BINDESHWARI RAM | Bahujan Samaj Party | 644 |
| PARAMILA DEVI | Jammu & Kashmir National Panthers Party | 523 |
| ABHISHEK PRAKASH | Sarvajan Kalyan Loktantrik Party | 447 |
| None of the Above | None of the Above | 3133 |
| AC No | Category | Poll Phases | Last Date of Nominations | Date of Polls | Result |
| 13 | (SC) | Phase IV | Oct 7th 2015 | Nov 1st 2015 | Nov 8th 2015 |
Harsidhi assembly constituencies is in eastern Champaran district and falls under eastern Champran Lok Sabha constituency. It comprises of Harsidhi and Turkaulia community development blocks. It has 2,15,426 eligible voters, out of whom 1,15,413 are men, and 1,00,012 are women. Harsidhi assembly constituency is reserved for Schedule Cast.
Located in the Purvi Champaran district of Bihar, Harsidhi assembly constituency, which was made a reserved seat before the last general assembly elections to Bihar, is currently represented by Krishana Nandan Paswan of the BJP who emerged victorious from the seat in the last assembly elections in 2010 by defeating Satish Paswan of the Rashtirya Janata Dal (RJD) by a good margin of 18064 votes. While 48130 votes were polled in favour of Krishana Nandan Paswan, Satish Paswan received 30066 votes and was distantly followed by Vijay Kumar Ram of the Congress who received 6202.
In 2010, the RJD and Ramvilas Paswan led Lok Janashakti Party (LJP) had contested the elections jointly. However equations have changed today. The BJP and the JD (U) have snapped their alliance and LJP is now a part of the NDA, the ruling dispensation at the Centre. The JD (U), the Congress and the RJD have come together to check the Modi juggernaut.
Earlier in 2005 Krishana Nandan Paswan had defeated Satish Paswan to win the Pipra assembly seat, then a reserved constituency.
Earlier Maheshwar Singh and Awadhesh Prasad Kushwaha had been slugging it out for the Harsidhi assembly seat since 1995. Awadhesh Prasad Kushwaha defeated Maheshwar Singh to win the seat in 1995 only to be defeated by him in the next elections in 2000.
In the next assembly election in the month of February in 2005, Awadhesh Prasad Kushwaha, then a LJP candidate, emerged victorious by defeating Maheshwar Singh, who contested on the ticket of the JD (U). However, in the next assembly elections in November, necessitated due to the hung assembly thrown by the February polls, both exchanged their parties and Maheshwar Singh got the better of the two.
In 2010, Awadhesh Prasad Kushwaha was elected from the Pipra assembly constituency. Harsidhi assembly constituency had earlier elected former Bihar Speaker Md. Hadaytullah Khan four times. He had won the seat in 1972, 1980, 1985 and 1990.
Harsidhi is one of the six assembly constituencies that combine to form the parliamentary constituency of Purvi Champaran which is currently represented by Union BJP minister Radha Mohan Singh of the BJP who retained the seat by defeating his nearest RJD rival by a margin of Binod Kumar Srivastava votes in the last Lok Sabha elections in 2014. Other five assembly constituencies are Govindganj, Kesaria, Kalyanpur, Pipra and Motihari.
Krishnanandan Paswan from BJP is contesting in Harsiddhi which is part of East Champaran district. The grand alliance has replaced the usual RJD candidate Satish Paswan with Rajinder Ram. Villagers say the choice of Ram against a Paswan, BJP MLA Krishna Nandan Paswan, helps the grand alliance. A Paswan versus a Paswan would have given the BJP the edge, the villagers claim. Besides, the sitting RJD MLA Satish Paswan has not done much for the constituency, say villagers.