Incumbent President Tarja Halonen has easily won the first round of Finland's presidential poll but faces a run-off after failing to take 50% of the vote.
Halonen and Niinisto will meet again on 29 January
The left-leaning Social Democrat leader Ms Halonen won 46.3% of the vote.
Conservative Sauli Niinisto came second with 24.1%, and will face her in a run-off ballot in two weeks time.
The election campaign was dominated by foreign policy issues, particularly traditionally neutral Finland's relationship with Nato.
Centrist Prime Minister Matti Vanhanen was third with 18.6% of the vote.
"It's a pity... but it's no use to complain," Ms Halonen said of the result. "I'm still in pole position."
Mr Niinisto, a former finance minister, was optimistic about his prospects in the next vote, which will be held on 29 January.
"It's not bad to start from second position," he said.
An estimated 4.2 million people are registered to vote in Finland.
Ms Halonen, a 62-year-old former lawyer and foreign minister, became the country's first woman president in the year 2000.
The powers of the Finnish head of state are largely focused on foreign policy - an area where there has been broad agreement between the president and government.
Both Ms Halonen and her main rival, Mr Niinisto, support Finland's EU membership, its co-operation with Nato and its close ties to former foe, Russia.