The fight is mainly between the ruling AIADMK's P. Saroja and DMK's V. Maran. All others are independents.
Around 2,500 police personnel have been deployed in the constituency.
The by-election in the hill station, around 360 km from here, was necessitated after AIADMK legislator C. Perumal died in July. Saroja is Perumal's wife.
This led to the AIADMK's strength in the 235-member assembly come down to 150. The DMDK is the second largest party in the house with 29 members, followed by the DMK with 23.
This will be the fourth assembly by-election in the state after the AIADMK came to power in May 2011. The AIADMK won all three earlier elections at Pudukottai, Sankarankoil and Tiruchirapalli (West) constituencies.
The vote count will be Dec 8.
According to election commission, apart from voter slips, SMS has also been sent to all voters whose mobile numbers were listed in the electoral data base giving the serial number of the voter identity card.
The SMS also includes slogans "Vote without note" and "Don't sell your future".
The total number of voters in Yercaud constituency is around 240,000 of which men constitute around 119,000 and women around 121,000.
--IANS (Posted on 04-12-2013)