In 1991, Monroe was asked by Guns N' Roses to appear on their "Use Your Illusion I" album, where he plays the harmonica and saxophone on the song "Bad Obsession". Monroe also later appeared on GNR's 1993 album, ""The Spaghetti Incident?"", where he sang on the cover of The Dead Boys' "Ain't It Fun". At the time, Monroe also joined Guns N' Roses on stage performing Honky Tonk Women together with the band members and Ronnie Wood of the Rolling Stones.