This is a timeline documenting the events of heavy metal in the year 1990.

Newly formed bands

Albums & EPs

Disbandments

• Atrophy (reformed in 2015)

Events

• Adrian Smith, Iron Maiden's lead guitarist, leaves the band to pursue a solo career. Janick Gers is hired to replace him.
• Metallica wins the first ever Grammy award in the category of Best Metal Performance for the song "One."
• The infamous Clash of the Titans tour is this year, headlined by bands such as Slayer, Megadeth, Anthrax, Testament, Suicidal Tendencies, and others.
• August 7: Extreme release their second album Pornograffitti. The album peaked at number 10 on the Billboard 200 album chart and sold very well, due to the success of its single "More Than Words", which reached #1 on the Billboard Hot 100 chart a year later.
• Judas Priest was involved in a multimillion-dollar lawsuit involving two Nevada teenager suicides allegedly caused by the song "Better by You, Better than Me". The band won the case.
• Faith No More's The Real Thing, carried by the single "Epic", also cracks the Billboard Top 10.
• Marty Friedman joins Megadeth replacing Jeff Young on guitar.
• Possessed frontman, Jeff Becerra is paralyzed from the waist down after being shot in a mugging on his way home from work.
• Lȧȧz Rockit, Death Angel, Sacred Reich and others are featured on the soundtrack of Leatherface: The Texas Chainsaw Massacre III.