Travellers arriving in Scotland from Poland and Turkey will now be required to self-isolate for 14 days.
Justice Secretary Humza Yousaf said the measure was being put in place because of a "significant increase in cases" from Poland.
For Turkey, he said it was clear that case numbers had been under-reported.
Meanwhile, those arriving from the Azores and Madeira will no longer need to quarantine due to the low number of cases of Covid there.
Mr Yousaf said people should "think long and hard before choosing to travel abroad", especially during the school holidays in the next few weeks.
A list of countries exempt from the quarantine rules is available on the Scottish government website.
As well as Poland and Turkey, the Caribbean islands of Bonaire, St Eustatius and Saba have been added to the quarantine list.
This means people arriving from any of these destinations from 04:00 on Saturday are required to self-isolate at home, or another specified address.
Mr Yousaf said: "At present all foreign travel carries a risk. Quarantine requirements could be imposed on those arriving on holiday abroad, just as we may make the decision to impose the same in Scotland.
"People should think very hard before committing to non-essential foreign travel."
He said: "Imposing quarantine restrictions on those arriving in the UK is our first defence in managing the risk of importing cases from communities with high risks of transmission. This is vital in our efforts to suppress the spread of the virus in Scotland."
Travellers face fines if they fail to comply with quarantine requirements after returning from abroad.