"When Love & Hate Collide" is a song by English rock band Def Leppard from their 1995 greatest hits album Vault, written by Joe Elliott and Rick Savage.

"When Love & Hate Collide" was written by lead singer Joe Elliott and bassist Rick Savage in 1990 during the composition and recording sessions for the band's fifth studio album Adrenalize.

The song was ultimately left off the track listing for Adrenalize with the band preferring newly-written and recorded "Have You Ever Needed Someone So Bad" according to guitarist Phil Collen.

According to new guitarist Vivian Campbell on the Best of liner notes, their record label wanted a "syrupy-sounding" single for a possible compilation album, but they had "nothing at all in that vein".

The decision to release Vault instead allowed the band to fully "close the door" on the Steve Clark era and to continue working on Slang.