Mr Viktor Yushchenko remains the clear favorite to win the re-run presidential election in the Ukraine today.
More than 33,000 polling stations opened at 8 a.m. (06.00 Irish time) in mild weather in the former Soviet republic and are due to close at 8 p.m. (18.00).
An exit poll is to be announced soon afterwards but it is uncertain when official results will be available. Some 12,000 foreign observers are monitoring the vote.
Mr Yushchenko is running against Prime Minister Mr Viktor Yanukovich, whose victory in last month's vote was overturned by the Supreme Court on grounds of mass fraud.
If Mr Yushchenko wins, he faces a huge task in transforming an economy that analysts say is still based largely on Soviet-era principles.
He must also tackle corruption inherent in a close relationship between large, favored business "clans" and a powerful bureaucracy.
Double-digit inflation and a high budget deficit will require fast and decisive action from the new leader of a country where growth has yet to transform standards of living for most ordinary people. Average wages are only $110 a month.