Switzerland was first introduced in . They replaced some of the former fast trains with their own identity. InterRegio trains run from region to region within Switzerland. One service extends to the German city of Konstanz, just across the border.

InterRegio trains are now very commonplace in Switzerland. The abbreviation is IR in a 45°-edgy font, white letters on red (). Since the early 2020s, most IR services are numbered and each has a distinct