Election returns from polling stations will come in after midnight, said the head of Ukraine's Central Elections Commission.
"I think that starting with midnight or one A.M. we will start receiving reports about the records of the election commissions - first from the smaller polling stations where ballot-counting will end sooner than at medium and large polling stations," CEC Head Mykhailo Okhendovsky said at a briefing in Kyiv, according to Interfax.
President Poroshenko has returned to Kyiv to vote, after making a surprise trip to the Donbas region.
"I am voting for our future, for the European direction in Ukraine's development and for government renewal. I am convinced that we will have a new government, a new pro-European coalition and a new parliament," he told reporters, according to Interfax. "I hope I will manage to form a powerful pro-European coalition, a pro-Ukrainian democratic coalition. I do hope that the Ukrainian people will make a very responsible choice today,"
Our correspondent Tom Balmforth is in Kyiv, talking to voters:
From RFE/RL's Ukrainian Service, Members of the Ukrainian military cast ballots at a polling station in Kramatorsk in the country's parliamentary elections on October 26. In the city of Lviv, soldiers wounded in the conflict in the country's east voted from their hospital rooms, where election workers brought ballot boxes.
The Ukrainian Embassy in Moscow says that "as many as 406 voters" cast their ballots by 4 p.m., surpassing the count for the 2011 parliamentary elections.
A candidate vying for a seat in the Rada dressed as Darth Vader was not allowed to cast a ballot, he told journalists.
"I have a passport, I showed it to the members of the electoral commission. To cut it short, they once again did not let me [vote]. It is disappointing. But the fact that I didn't vote does not mean that the new Ukrainian empire will not be built," the candidate with the Internet Party told journalists in Kyiv.
RFE/RL's Carl Schreck reported that 16 Darth Vaders registered for the ballot for the elections.