Some 1,700 reformers and critics of Iranian President Mahmoud Ahmadinejad's hard-line policies have been banned from the polls by an unelected body of clerics and legal experts due to an alleged lack of commitment to Islamic values and the 1979 Islamic Revolution.
Reformists currently hold around 40 seats in the 290-seat national assembly.
A number of conservative candidates have also expressed concern over Ahmadinejad's increasingly 'fiery' rhetoric.
Iranian authorities have urged a large turnout in the polls to show support for the Islamic Republic and to defy its "enemies" - the United States and other Western states.
The UN Security Council passed a resolution earlier this month imposing a third round of economic sanctions on Iran over its nuclear program. The U.S. and its allies believe that the program is a cover for the development of nuclear weapons, while Iran insists that it is intended solely for the peaceful production of electricity.
Under the new sanctions, the accounts of certain Iranian companies and banks will be frozen, and goods leaving and entering the Islamic Republic will be subjected to inspections.
"Active participation by the wise and decisive people of Iran in the fulfillment of their political and religious duty [the polls] will yet again dishearten imperious world powers, especially the U.S.," Iranian Supreme Leader Ayatollah Ali Khamenei told crowds at a rally in Tehran recently.
In a thinly-veiled criticism of the Bush administration, Khamenei went on to say that, "Those who stand for democracy are clearly set against democracy and elections in our country."
However, inflation is a significant issue in Iran, with many ordinary Iranians more concerned about spiraling food prices than the country's "integral right" to nuclear power.
Ahmadinejad is not expected to be able to vote in the polls as he is currently in Senegal attending an Organization of the Islamic Conference summit and Iranian laws do not allow overseas voting.
Relations between Russia and Iran are not expected to be affected by the outcome of the polls.
"Any political force coming to power in these polls will maintain a policy of neighborly relations with the Russian Federation," Kazem Jalali, a spokesman for Iran's parliamentary committee on national security and foreign policy earlier told RIA Novosti.
Polling booths opened across Iran at 8:00 a.m. local time (04.30 GMT). The results of the elections are to be officially announced before March 20. Turnout is expected to be between 50 and 70%.
