Iranians packed polling stations from boutique-lined streets in north Tehran to conservative bastions in the countryside as the country went to the polls.
They had a choice that has left the nation divided and on edge: keeping hard-line President Mahmoud Ahmadinejad in power or electing a reformist who favours greater freedoms and improved ties with the US.
Crowds formed quickly at many voting sites in areas considered both strongholds for Ahmadinejad and his main rival, reformist Mir Hossein Mousavi, who served as prime minister in the 1980s and has become the surprise hero of a powerful youth-driven movement.
At several polling stations in Tehran, mothers held their young children in their arms as they waited in long lines.
"I hope to defeat Ahmadinejad today," said Mahnaz Mottaghi, 23, after casting her ballot at a mosque in central Tehran.
Outside the same polling station, 29-year-old Abbas Rezai said he, his wife and his sister-in-law all voted for Ahmadinejad.
"We will have him as a president for another term, for sure," he said.
The fiery, month-long campaign unleashed passions that could bring a record turnout. The mass rallies, polished campaign slogans, savvy internet outreach and televised debates more closely resembled Western elections than the scripted campaigns in most other Middle Eastern countries.
In a sign of the bitterness from the campaign, the Interior Ministry - which oversees voting - said all rallies or political gatherings would be banned until after results are announced, which are expected on Saturday.
The outcome will not sharply alter Iran's main policies or sway high-level decisions, such as possible talks with Washington. Those crucial policies are all directly controlled by the ruling clerics headed by the unelected Supreme Leader Ayatollah Ali Khamenei. But Mousavi has offered hopes of more freedoms at home. If elected, he could try to end crackdowns on liberal media and bloggers and push for Iran to embrace President Barack Obama's offer of dialogue after a nearly 30-year diplomatic freeze.
