Iranians have voted in two elections seen as the first test of public support for President Mahmoud Ahmadinejad since he came to power.
This will be the first test of public support for Mr Ahmadinejad
Voters were choosing new local councils and a powerful clerical body known as the Assembly of Experts.
Reformists are hoping for a comeback following comprehensive defeats by conservatives in recent years.
Officials said turnout was high, with polling was extended by three hours in many places, to 2200 (1830 GMT).
No figures were immediately available, but Mojtaba Hashemi Saremeh, the deputy interior minister in charge of elections, described the turnout as "unprecedented".
Reformists and conservatives have both run campaigns urging people to cast their ballots. About 46.5 million Iranians are eligible to vote.
There has traditionally been a low turn-out for the assembly elections, with many Iranians scarcely aware of its deliberations.
In theory, the Assembly of Experts is the most powerful body in Iran's complex network of religious institutions.
Its job is to elect, dismiss and supervise Iran's top political figure, the Supreme Leader - currently Ayatollah Ali Khamenei.
The BBC's Frances Harrison in Tehran says voting in the capital started slowly but picked up in the afternoon to a brisk pace.
There is still some confusion over how and where the votes will be counted, she says.
Opponents of the government want the votes to be counted in the polling stations, rather than centralised locations, to reduce what they say is the possibility of fraud, our correspondent says.
Mr Ahmadinejad said he was sure Iranians would back the elections
Many government supporters said they had voted as a show of solidarity with Iran's Islamic system, our correspondent says, and as a blow to the US and Israel, who claim the Iranian government has no popular support.
But some Iranians refuse to vote, not wanting to endorse Iran's electoral system where the authorities vet all candidates, our correspondent adds.
The reformists are barely present in the assembly race, because candidates must be passed by a conservative panel.
Analysts are watching to see whether the body will be dominated by conservatives aligned with Mr Ahmadinejad or pragmatists close to the former president, Akbar Hashemi Rafsanjani.
'Don't boycott polls'
The local council elections, in contrast, are likely to witness a higher turn-out and will provide a clearer reflection of trends in public opinion, analysts believe.
Iranians are voting in two sets of elections
Assembly of Experts poll: Powerful clerical body which supervises the Supreme Leader
Local council polls: More than 250,000 candidates for around 100,000 seats nationwide
46.5 million eligible voters
Reformists are hoping for gains after being roundly defeated in polls in 2003, in which turn-out was very low.
"Boycotting elections has not worked in previous elections, please vote for the reformist candidates," a reformist campaign text message said.
But many are backing the conservatives.
"I think Ahmadinejad supporters will win," Mohsen Jahanian, a political science teacher, told Reuters news agency. "Iranians still do not trust reformists to vote for them."
"I will vote for Ahmadinejad's supporters," said taxi driver Hasan Alimardani.
"He is the people's man, he goes to remote places and sees the problems at first hand. We need to give him time to deliver on his promises."
The municipal council race in Tehran will be keenly watched as a barometer of political sentiment. Reformists dominated the council until 2003, but conservatives currently hold all the seats.
Reformists are hoping to win some seats, while two competing conservative factions - one loyal to Mr Ahmadinejad and the other to Tehran's current mayor, Mohammad Baqer Qalibaf - are challenging each other.
Mr Ahmadinejad emphasised the importance of the elections on Iranian TV.
"I am certain that our dear people will be present on the scene tomorrow and will demonstrate their grandeur and honour to the world," he said.