At sharp 8 am, the counting process started in 839 halls spread over in the five states involving 43,982 personnel.
The Election Commission has made elaborate arrangements for the massive exercise and pressed into service nearly 17,700 Central security personnel to provide a three-tier security.
The entire process, which would decide the fate of several political leaders, would be videographed to prevent any malpractice. According to Chief Election Commissioner S Y Quraishi, the poll outcome is expected by "early lunch".
"Efficient and secure arrangements are in place for counting and declaration of results," Quraishi said.
The counting is taking place in 142 counting halls in Assam, 140 in Kerala, 11 in Puducherry, 234 in Tamil Nadu and 312 in West Bengal. While Kerala has an assembly strength of 140, Assam has 126, Tamil Nadu 234, Puducherry 30 and West Bengal 294.
A total of 14.16 crore voters exercised their franchise in the five states which was 20 per cent of the total 72.8 crore electorate in the country with Tamil Nadu and West Bengal registering "all time record turnouts".
Stakes are high in West Bengal where post poll surveys predict that Mamata Banerjee's Trinamool Congress is expected to oust CPM-led Left Front which is ruling the state for 34 years.
CPM is hopeful that like many previous occasions it would prove its detractors wrong and romp home for the eighth term.
In view of the political clashes witnessed in the state in the run up to the elections, the Central forces will stay in the state till May 23 to tackle the post-poll situation as per the EC directive.
The surveys also gave a close finish in Tamil Nadu where the two Dravidian parties, DMK and AIADMK vied with each other to woo voters.
For AIADMK's Jayalalithaa, it will be a battle to return to power after a hiatus of five years. DMK, which suffered setbacks on account of 2G spectrum scam and corruption involving the first family members, is seeking a second successive term.
In Kerala, the surveys gave a mixed picture with one predicting an upper hand for the ruling Left Front.
In Assam, surveys foresee that the ruling Congress would retain power.
The counting of votes for the high-profile by-election to Kadapa Lok Sabha in Andhra Pradesh will also be taken up today, which will determine the political future of Y S Jaganmohan Reddy, son of former Andhra Pradesh Chief Minister Y S Rajasekhara Reddy.
For Jagan, it was a fight to establish his political credentials after he floated his own political party YSR Congress.
For the Congress, its prestige is at stake in Kadapa as the Lok Sabha seat always remained in its kitty, thanks to YSR.
Jagan's mother Vijayalakshmi also contested the Pulivendula Assembly seat.