18 Greatest Hits is a compilation album by Polish group 2 Plus 1, released in 1991 by Sonic Records. It was 2 Plus 1's first album released directly on CD, and their last authorised release in the original line-up, before Janusz Kruk's death in 1992. Branded as a greatest hits album, the CD featured majority of the band's most notable hits, although ignored their English-language material. The album was re-released as 21 Greatest Hits five years later with slightly altered track listing, and the original 1991 issue is now a rare collectors' item.