Voters turned up in good numbers since the polling began at 7 am in Kerala and an hour later in Tamil Nadu and Puducherry with no untoward incident reported so far.
The fate of three southern heavyweights --- Tamil Nadu Chief Minister and DMK President M Karunanidhi, his Kerala counterpart V S Achuthanandan and AIADMK chief Jayalalithaa will be decided today in one of the closest electoral battles in Tamil Nadu and Kerala.
In the union territory of Puducherry also, voting to elect 30 Assembly members began on a brisk note with large queues before the polling booths.
Tamil Nadu, with 234 member Assembly, is witnessing tight electoral race between the fronts led by DMK and AIADMK.
In Kerala with 140 Assembly segments, the ruling CPI(M)-led LDF is battling to buck the trend of alternate fronts coming to power once in every five years.
A total of 971 candidates are in the fray in Kerala, many of them are independents.
Tight security arrangements have been put in place in Tamil Nadu, where the Election Commission is keeping a hawk eyed vigil amid allegations of distribution of money to woo voters.
In politically-sensitive Kerala, over 1.25 lakh security personnel including para military forces, have been deployed in 20,578 polling stations.
Tamil Nadu and Kerala have a total electorate of 6.91 crore and Puducherry 8.1 lakh voters.