...The race is said to be the closest since Ghana's independence
Millions of Ghanaians have turned out at the polls to elect a new president and 200 members of parliament.
There were long queues at many polling stations more than an hour before polling officially opened at 0700 GMT.
The director of elections, Albert Kofi Arhin, says polling will be extended beyond the 1700 GMT deadline to cater for the large voter turn-out.
One little project that I'm seriously considering is to take on the battle against these malaria mosquitoes Outgoing President Rawlings
The outgoing President, Jerry Rawlings, arrived to vote at 1100 GMT, and asked the 50 or so voters in the queue: "Is it OK if I go ahead of you?"
"Yes, yes," they responded.
President Rawlings told news reporters that he was going to fly around the country in a helicopter "to see if everything is alright".
The election, expected to be the closest since Ghana's independence in 1957, marks the end of Mr Rawlings' 20-year rule.
Rawlings's future
President Rawlings said, "Let us just hope that the election will be without fraud and we'll accept the results from the electorate."
Rawlings, to embark on war against malaria
"[John] Kufuor (New Patriotic Party candidate) wants to come into office, anybody including Professor Mills (Vice-President and ruling party candidate) wants to come into office, we'll welcome them provided they do it in a free, genuine and sincere manner," said Mr Rawlings.
This was essentially the theme of a nationwide radio and television broadcast by the outgoing president last night.
Mr Rawlings used the occasion to discuss his future after his presidency.
"One little project that I'm seriously considering is to take on the battle against these malaria mosquitoes. How I'm going to go about it I haven't quite worked out yet, but I think I'll need a break first."
Security operative
Voting was generally orderly. However, at one polling station at North Kaneshie in Accra, a man held up voters with a gun for an hour, saying that he would not allow voting to start in the absence of police.
Voting was reportedly peaceful and orderly
He was later driven away but Joy FM radio reported that the man had been set free, sparking suspicion that he may have been a security operative.
Forty-eight New Patriotic Party (NPP) polling agents were arrested overnight in the governing National Democratic Congress (NDC) stronghold of the Volta Region, on suspicion that they were thugs.
They were driven to Accra, but released after party officials intervened.
Nine others are reportedly being held at Akatsi, also in the Volta Region.
Great grandmother
President Rawlings was not the only one who was allowed by voters to jump the queue.
84-year-old Baddoo could not wait to vote
Mary Baddoo, 84, went straight ahead of the rest on the queue the moment she arrived at a polling station in Osu, Accra. She is a great grandmother and did not need to ask for a favour.
She said she has voted many times in her life. "I always do. It's good to get someone who will help us in the nation."
A driver in Accra, 32-year-old David Anim, said: "I'm very happy to come and vote this morning because with my small thumbprint, me too I can help to choose a new president."
"I'm here to exercise my franchise, said Kofi Agbesi, 47, a photographer, who was voting at the same polling station as President Jerry Rawlings. "It's the power of every citizen," he said.
Mr Mills and his main challenger, Mr Kufuor of NPP are the front-runners in what is seen as a close race for presidency.
Analysts predict a run-off between the two men, to be held within 14 days. Search BBC News Online