Rust In Peace (1990–1991)

Following Mustaine's new found sobriety, Megadeth began a lengthy search for a new lead guitarist. Lee Altus of Heathen was among those who auditioned, as was Eric Meyer of Dark Angel fame. Meyer had been invited to join the band following Chris Poland's departure, but had declined in order to remain in Dark Angel.

Dimebag Darrell Abbott of then-obscure Pantera also auditioned, and was initially offered the spot. Darrell, however, would not join without his brother, Pantera drummer Vinnie Paul Abbott, and, having already hired Nick Menza, the band was forced to turn Darrell down.

In 1987, a 16-year-old Jeff Loomis (of Sanctuary, and later Nevermore) auditioned. Afterwards, Mustaine complimented Loomis on his playing, but rejected him because of his age. Loomis later saw Cacophony with Marty Friedman and Jason Becker on tour, and told Friedman, who had just released his first solo effort, Dragon's Kiss in 1988, of the experience. Friedman eventually auditioned for the spot, but was initially rejected by Mustaine for having multicolored hair. However, after undergoing what Mustaine called "Rock School 101", Friedman officially joined Megadeth in February 1990.

A revitalized Megadeth entered Rumbo Studios in March 1990 with co-producer Mike Clink to begin work on what would become their most critically acclaimed album to date, Rust In Peace. For the first time in their career, the band worked sober in the studio, alleviating many of the problems faced recording previous albums. Clink was also the first producer to successfully produce a Megadeth album from start to finish, without being fired.

Released worldwide on September 24, 1990, Rust In Peace was a hit with fans and critics alike, debuting at #23 on the Billboard Top 200 in the US, and #8 in the UK. The album showcased a much tighter sound, with Mustaine's writing style adopting a rhythmically complex progressive edge, prompting Allmusic to cite Rust in Peace as "Megadeth's strongest musical effort". The album featured the singles "Holy Wars... The Punishment Due", and "Hangar 18", both of which received music videos, and remain live staples. Rust in Peace went on to sell more than a million copies in the US, and received Grammy nominations in 1991 and 1992 for Best Metal Performance.

In September 1990, Megadeth joined Slayer, Testament and Suicidal Tendencies for the European "Clash of the Titans" tour, and in October, they were added as the opening band on Judas Priest's Painkiller tour, culminating with a performance to 140,000 people in January 1991 at Rock in Rio 2 festival in Brazil.^{[citation needed]} Following the success of the European tour, a "Clash of the Titans" US tour began in May 1991, featuring Megadeth, Slayer, Anthrax and opener Alice in Chains. In July, Megadeth's "Go to Hell" was featured on the Bill & Ted's Bogus Journey soundtrack, and shortly after "Breakpoint" was featured on the Super Mario Bros soundtrack. In 1991, Megadeth also released their first home video, Rusted Pieces, which contained six of the band's music videos, along with a video interview with the band.