Antananarivo, where Ravalomanana began his political career as mayor, accounts for more than 600,000 eligible voters from the country's total of nearly seven million.
But Ravalomanana is also popular in the countryside where the reforms of his first term had a greater effect on reducing poverty than in the big cities.
Early results from a few districts in Toamasina province, a traditional opposition stronghold, showed Ravalomanana in front of Roland Ratsiraka, the nephew of Didier Ratsirakam, the former president.
Ravalomanana, 56, who built a business empire after selling yoghurts from the back of his bike, beat Ratsiraka in 2002 with a mixture of mass demonstrations and military force, after the long-term Marxist president contested Ravalomanana's 2001 election victory.
The current president will win if he takes more than 50 per cent of the vote. Without this margin, a second round will be held at the end of December.
Ravalomanana has conducted a slick campaign, touring the country by helicopter and used his wealth, media empire and presidential power to eclipse his 13 rivals.
Despite torrential rain flooding roads and cutting electricity supplies, turnout was approximately 60 per cent, and several polling stations remained open past the official closing time.
Only one incident took place amid peaceful elections on Sunday, in the south coast town of Toliara, where voters burned a ballot box, forcing a polling station to close.
Officials said several people were arrested after rock barricades were put on roads into the central town of Fianarantsoa in an attempt to obstruct voters.
Ravalomanana campaigned on his record of economic reforms and infrastructure building, which includes a new network of roads that has improved access to markets for farmers.
The opposition says his policies are mistaken and he has not done enough to reverse poverty on the island, which stretches for 1,590km off the east coast of Africa.