Iranians are going to the polls on Friday to elect 290 members of the country's parliament, the Majlis, al Jazeera television reports.
It is the first national ballot since the disputed 2009 presidential elections were won by President Mahmoud Ahmadinejad. Mass protests against the official result were met by a heavy government crackdown and dozens of opposition activists were put on trial.
Friday's vote is seen as a battle between Ahmadinejad's supporters and those of the Islamic republic's supreme leader Ayatollah Ali Khamenei.
State TV footage showed Khamenei casting his vote in Tehran.
Iran faces increasing international pressure over its disputed nuclear program, which the West fears is being used to build atomic weapons. Iran insists its nuclear activities are entirely peaceful and has vowed to take a preemptive military action against its enemies to protect its national interests.