Iranian state media has said that turnout in yesterday's parliamentary elections was high.
The interior ministry said that voting deadlines had been extended several times because of long queues.
However, opposition websites and bloggers described the voting as lacklustre and accused authorities of manipulating turnout figures.
The election results are expected to be announced on Monday.
The vote in Iran is only a limited test of political opinion since leading reformist groups stayed out of what became a contest between the camps of Supreme Leader Ayatollah Ali Khamenei and President Mahmoud Ahmadinejad.
"Whenever there has been more enmity towards Iran, the importance of the elections has been greater," Mr Khamenei, 72, said after casting his vote before television cameras.
"The arrogant powers are bullying us to maintain their prestige. A high turnout will be better for our nation ... and for preserving security."
His hopes for wide participation received a boost when Iranian authorities had to delay the end of voting by five hours to let more people cast their ballot, closing polling stations at 11pm (7.30pm Irish time).
Iranian media says the turnout was over 65%.
Ballots are counted manually and Iranians may have to wait three days for full results. Some media reports suggested that rivals of President Ahmadinejad won in some constituencies.
The semi-official Mehr news agency said the president's sister, Parvin Ahmadinejad, failed to secure a seat in the parliament. She was running from the central town of Garmsar, the home-town of Mr Ahmadinejad.
Pro-reform candidate Mohammadreza Tabesh was elected from the birth place of moderate former president Mohammad Khatami. Results in major cities like Tehran have not been announced yet.
The vote will have scant impact on Iran's foreign or nuclear policies, in which Mr Khamenei already has the final say, but could strengthen the Supreme Leader's hand before the presidential vote next year. Mr Ahmadinejad, 56, cannot run for a third term.
