Voters in Scotland have gone to the polls in the first test for the Scottish National Party (SNP) since the arrest of its former leader Nicola Sturgeon over allegations of financial irregularities.
The polls closed at 10pm with a result expected in the early hours of tomorrow.
The Glasgow suburban seat has swung between the SNP and Labour in the last four elections since 2015.
The by-election was called because Margaret Ferrier - elected for the SNP - was kicked out of the party after breaching Covid-19 restrictions by travelling between London and Glasgow after testing positive for the virus.
She was forced out by a petition of voters when she refused to resign.
The vote also follows the arrest in June of Ms Sturgeon, her husband Peter Murrell, who was the SNP's chief executive, and the party's treasurer Colin Beattie.
All three have rejected allegations of financial misconduct.
During the by-election campaign, the cost-of-living crisis dominated with Labour's refusal to commit to removing a cap on child benefits emerging as one issue.
However, the party is strongly favoured to retake the seat.
Labour has to be able to win convincingly in Rutherglen and Hamilton West to maintain its momentum towards victory in the next UK general election, expected to take place next year.
It currently has just one MP in Scotland - down from 41 in 2015.
Fourteen candidates are contesting the seat, including Katy Loudon for the SNP, Labour's Michael Shanks and Conservative Party hopeful Thomas Kerr.
The election is the first in Scotland to require voters to show photo identification before they are allowed to cast their ballot following a change in the law.
Additional reporting PA
