The country's 6,150 polling stations opened at 7:00 am (0700 GMT) and were scheduled to close 10 hours later.
Dozens of people were wounded in violent inter-party clashes during the electoral campaign and security was high at polling stations across the country Saturday.
Opposition politician Ernest Koroma is squaring off against outgoing Vice President Solomon Berewa to take over from President Ahmad Tejan Kabbah, who led the country for two five-year terms during and after the war which ended six years ago.
Kabbah is legally barred from seeking a third term.
Some 2.6 million voters are registered to vote in only the second elections since the end of the civil war six years ago and the first Sierra Leone is organising after some 17,500 UN peacekeepers pulled out in 2005.
"I am voting for change," said one voter, Tamba Sillah, whose right arm was hacked off by rebels during the decade-long civil war.
"The past government did not do anything for us amputees. It was all promises, promises and promises," he said as he queued up to vote with scores of others at a Freetown school.
Although the numbers of voters appeared early on to be lower than in the first round of voting last month, Henry Pratt, an election officer at one city centre polling station remained upbeat.
"There is no voter fatigue that was feared," he said.
An African Union observer witnessing the start of voting said: "we are satisfied at the commencement of the polls from what we have seen so far".
Last Mod: 08 Eylül 2007, 14:50