There are 450 parliamentary seats in the legislature, dominated by President Viktor Yanukovich's Party of Regions, and about 35 million eligible voters, Euronews.net reported.
About 800 observers from 42 countries were deployed to polling stations for the election, which follows widespread allegations of corruption by members of Yanukovich's party, the Kiev Post reported.
Opposition candidates have accused his party of using political intimidation on voters, Euronews said.
Yanukovich's key rival, former Premier Yulia Tymoshenko is serving a 7-year prison sentence for abuse of power. She issued warnings the country could fall into dictatorship if Yanukovich is re-elected and urged voters not to boycott the election, the reports said.
Tymoshenko's pro-Western Fatherland party was also facing opposition from the leftist Punch party, led by a former boxer.