The by-election is being held following the death of MP David Cairns Polling stations have closed in Inverclyde to elect a new member of the UK Parliament.
Labour is defending a 14,416-vote majority in the seat, which is also being contested by the Conservatives, SNP, Liberal Democrats and UKIP.
The by-election is being held to find a replacement for David Cairns who died from acute pancreatitis in May at the age of 44.
A result is expected in the early hours of Friday morning.
Sophie Bridger is standing for the Liberal Democrats, Iain McKenzie for Labour, Anne McLaughlin for the SNP, Mitch Sorbie for the UK Independence Party and David Wilson for the Conservatives.
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