"What Hurts the Most" is a song written by American songwriter Jeffrey Steele and English songwriter Steve Robson. Initially recorded by country music artist Mark Wills in 2003 on his album And the Crowd Goes Wild, it was covered by Bellefire a year later. However, the first version to be released as a single was by pop singer Jo O'Meara in 2005, from the album Relentless. Later that year, country band Rascal Flatts covered the song as well, releasing it as the first single from the 2006 album Me and My Gang, topping the U.S country and adult contemporary charts with it. German band Cascada later had international chart success with the song in 2007. It was also covered by Eden in 2008.