Voters turned up in good numbers to cast their votes in the bypoll in which both ruling AIADMK and Opposition DMDK are seeking to increase their strength by one more in the 234-member Tamil Nadu Assembly.
Kathik Thondaiman of AIADMK and DMDK's Jahir Hussain are in the fray among 18 others even as other opposition parties, DMK and MDMK which had fought the earlier Sankarankoil bypoll, have not fielded their candidates.
Polling has been peaceful so far, police said.
EVMs are being used for the polling process in 224 booths in the constituency. Counting is scheduled for June 15.
AIADMK and DMDK have 149 and 29 members respectively in the Assembly.
The bypoll was necessitated following the death of CPI legislator SP Muthukumaran who was killed in a road accident on April 1.