The train operator warned earlier this week that it was being forced to cancel services because increasing numbers of ScotRail staff were having to self-isolate.
It comes as Omicron continues to spread and after First Minister Nicola Sturgeon announced a wave of new restrictions, coming into force on Boxing Day, in a bid to curb infections.
What ScotRail services are cancelled?
At the time of writing, ScotRail has listed 143 services across Scotland as being cancelled.
While some of these cancellations are due to normal issues, such as signal faults, most are a result of staff members being taken ill.
Services between Glasgow and Edinburgh, Gourock and Glasgow, Glasgow and Kilmarnock, and Neilston and Glasgow are among those which have been cancelled today.
To find the full list of cancellations, visit the ScotRail journey checker website.