Ukrainians are voting for a new parliament hoping to pull the country out of political turmoil.
President Petro Poroshenko, who is looking to cement his power in parliament to put the country on a pro-western path, called the election "historic".
"It's time to complete a full reset of power. I believe in a deep upgrade and rejuvenation of parliament. You'll see, it will be a radically new parliament. I have enough political will to implement the developed strategy of reforms. But I also need the majority in parliament. Reformist majority, not a corrupt one. Pro-Ukrainian and pro-European, not pro-Soviet," he said in a televised address to the nation on the eve of polling.
"We are building our new Ukrainian home on a reliable basis of European values and patriotic enthusiasm of the people of Ukraine. Vote for Ukraine – united, single, indivisible and European!" said Poroshenko.
More than 36.5 Ukrainians are eligible to vote while about 4.8 million people will not take part in the election.
The pro-Russian separatists who control the eastern Ukrainian regions of Donetsk and Luhansk, which have a population of about three million voters, have banned the vote. About 1.8 million people in Crimea, which was annexed by Russia, will also not participate.
As a result, 27 seats in the 450-member parliament will remain vacant.
The Ukrainian president's Petro Poroshenko Bloc, comprising the Solidarity Party and former boxer Vitali Klitschko's Udar, is expected to do well in the election.
Prime Minister Arseniy Yatsenyuk's People's Front is also tipped to enter parliament along with other nationalist parties.
As the pro-Russian forces have been weakened by the political upheaval in recent months, both the Communist Party and former president Viktor Yanukovych's Party of Regions are taking part in the election.