Voters have been tuning out to cast their votes since 8 AM. The main contest is between BJP and Congress.
Prominent candidates in the fray include E Dwijamani (INC), M Dhanabir (BJP), Th Laiba Manipur State congress Party (MSCP), Y Radheshyam (ITC) and M Amutombi Manipur Peoples Party (MPP).
The by-election was necessitated by the death of Maibam Kunjo (Trinamool Congress), a former information minister, three months ago. Maibam Dhanabir, BJP candidate in Hiyanglam constituency, is his eldest son.
Of the 24,000 voters, eight per cent exercised their franchise in the first two hours of voting, election officials said.