The process began at 8:00 a.m. on Saturday and the results are expected by the afternoon.
The election was held for 59 out of 60 seats in each of the three Northeastern states.
In Nagaland, the key contenders are Nationalist Democratic Progressive Party (NDPP) and the Naga People's Front (NPF).
In this election, the Bharatiya Janata Party (BJP) has forged an alliance with the NDPP, but has also maintained ties with its ally for 15 years, NPF.
In Nagaland Assembly polls, the key candidates are Neiphiu Rio (NDPP), Biplap Deb (BJP), TR Zeliang (NPF), Yanthungo Patton (BJP), K L Chishi (BJP) and Kewekhape Therie (INC).
In Meghalaya, the Congress Party, which has been in power for the last ten years, is expected to face a tough fight from the National People's Party (NPP) and BJP.
The Congress Party has fielded 59 candidates, while the BJP put up nominees in 47 constituencies. For the first time, Meghalaya Chief Minister Mukul Sangma contested from two seats.
Meanwhile, Tripura will see a tough fight between BJP and the Left government that has been ruling the state for 25 years.
The much-awaited counting in this north-eastern state will decide the electoral fortunes of 292 candidates, including 23 women.
The Congress Party fought elections on 59 seats, while the All India Trinamool Congress on 24 seats.
While the CPIM-M fielded 57 candidates; the Communist Party of India (CPI), the Revolutionary Socialist Party (RSP), and the All India Forward Bloc (AIFB) fielded one candidate each.(ANI)