Many Zimbabweans boycotted their one candidate-election today but witnesses and monitors said government militias forced people to vote for 84-year-old President Robert Mugabe in some areas.
The vote, held despite a storm of condemnation from inside and outside Africa, was denounced as a sham by Western powers and opposition leader Morgan Tsvangirai.
Mr Mugabe, in power for 28 years, stood alone after Mr Tsvangirai withdrew six days ago because of state-backed violence and intimidation.
Mr Tsvangirai and his Movement for Democratic Change, who say the vote is a farce, urged people to abstain but said they should vote if their lives were in danger.
"Whatever might happen, the results...will not be recognised by the world. No matter what you are forced to do, we know what is in your heart. Don't risk your life. The people's victory may be delayed but it won't be denied," he said in a statement.
Mr Mugabe is the sole candidate in today's election
The G8 group of rich nations lambasted Zimbabwe for going ahead with the vote and the United States said the UN Security Council may consider fresh sanctions on Zimbabwe next week.
Mr Mugabe voted with his wife at Highfield Township, on the outskirts of Harare. Asked how he felt, he told journalists: "Very fit, optimistic, upbeat," before being driven away.
Turnout was thin at many polling stations in the capital Harare, unlike parliamentary and presidential elections in March when people queued from the early hours.
"There is no doubt turnout will be very low," said Marwick Khumalo, head of monitors from the Pan African Parliament.
The Zimbabwe Electoral Commission said the vote was going well. "Everything is well on course and people are voting peacefully," deputy chief elections officer Utoile Silaigwana told state radio.
Thousands of polling officers have been deployed across the country and ballot boxes and papers have been distributed to more than 8,000 polling stations.
Mr Tsvangirai said voters were being ordered to record the serial numbers of their ballot papers to identify how they cast their ballots. Pro-Mugabe militias had threatened to kill anybody abstaining or voting for the opposition, he claimed.
Voters had their little finger dyed with purple ink.
Mr Tsvangirai said he understood South African president Thabo Mbeki planned to recognise Mr Mugabe's re-election. But he said it would be a "dream" to expect his MDC to join a national unity government with Mr Mugabe's ZANU-PF.
Mr Mbeki, the designated regional mediator in Zimbabwe, has been widely criticised for a soft approach towards Mr Mugabe despite an economic crisis that has flooded South Africa and other countries with millions of refugees.
Mr Tsvangirai won the March 29th poll but fell short of the majority needed for outright victory.
The MDC says Mr Mugabe's ZANU-PF militants will force people to vote today, especially in rural areas where the veteran leader lost support during the first round.
Mr Mugabe (84), has presided over Zimbabwe's economic collapse with hyper-inflation, 80 per cent unemployment, food and fuel shortages. A loaf of bread now costs 6 billion Zimbabwe dollars, or 150 times more than at the time of the first round of elections.
The MDC says nearly 90 of its supporters have died in political violence which it blamed on ZANU-PF supporters. Mr Mugabe says the opposition has been responsible for the violence.