Iranian Interior Minister Abdolreza Rahmani Fazli says results from Iran's second round of parliamentary elections will be announced on May 1.
He made the statement on Iranian state television as Iranians went to the polls on April 29. He said that the elections will decide 68 undecided seats in the 290-seat legislature.
The voting is in constituencies where candidates failed to get 25 percent of votes cast in the first round.
The elections, in which 17 million people were eligible to participate, will determine the makeup of Tehran's parliament, where no party currently holds a majority.
President Hassan Rohani's moderate and centrist allies made big gains in the first round of elections on February 26, but they failed to win a majority. They campaigned on promises to encourage foreign investment, support moves for greater diplomatic rapprochement, and seek social reforms at home.
Mehdi Saadatmandi, who voted in Robat Karim, a city southwest of Tehran, said he came to the ballot box "to finish what was done in the first round".
"If the economy is fixed, the politics will be fixed also and if the parliament is in line with the government then things will move forward much better," the 50-year-old said, opting for the reformists.
However, conservatives have appealed to voters on promises to limit Iran's opening up to the West.
"We should protect the country from the arrogant powers and their infiltration," said Zahra Karimdoost, a schoolteacher in Robat Karim who voted conservative, referring to the United States
The new parliament will begin its session on May 27. It has no direct control over major policy matters but it can back the policies of Rohani to bolster the economy.
International sanctions were lifted in January in exchange for curbing Iran's nuclear program under a deal reached with world powers in 2015.