Megadeth releases "Countdown to Extinction"

In January 1992, Megadeth entered Enterprise Studios in Burbank, California with co-producer Max Norman.

Norman, who had mixed Rust in Peace, would be integral in Megadeth's resulting musical makeover, pushing for shorter, less complicated, and more radio-friendly songs. The band spent four months in the studio with Norman, writing and recording what would become Megadeth's most commercially successful effort, Countdown to Extinction. The album was the first to feature writing contributions from each band member, and was even named by drummer Nick Menza.

On July 14, 1992, Capitol Records released Countdown to Extinction. The album was an instant hit, debuting at #2 on the Billboard Top 200 album charts in the US, and #5 in the UK. Anchored by the Mainstream Rock hits "Symphony of Destruction" (#29), the album quickly went double platinum in the US, and received a Grammy nomination for Best Metal Performance in 1993. The album's title song, "Countdown to Extinction" also gave Megadeth the distinction of being the only metal band to ever win the "Doris Day Music Award", presented to the band by the Humane Society of the United States in 1993 for "spotlighting species destruction and the horrific 'sport' of canned hunts".

The band released their second home video Exposure of a Dream, in November 1992, continuing in a similar to fashion to Rusted Pieces, the release featured all music videos previously released from Countdown. Megadeth began their world tour in support of Countdown to Extinction in December 1992 with Pantera and Suicidal Tendencies, followed by a North American tour beginning in January 1993 with Stone Temple Pilots. Just one month into the North American tour, however, the band was forced to cancel all remaining shows, including dates scheduled in Japan, as Mustaine again fell into substance abuse, and ended up in the hospital emergency room. After a seven week stint in rehab, Mustaine emerged clean once again, and the band returned to the studio to record "Angry Again", a song which was featured in the 1993 film Last Action Hero, and later nominated for a Grammy in 1994.

In June 1993 Megadeth returned to the stage, appearing as "special guests" at Metallica's Milton Keynes Bowl Festival, marking the first time the former bandmates played the same stage in ten years. The pairing prompted Mustaine's on stage announcement that "The ten years of bullshit is over between Metallica and Megadeth!", although problems would later resurface between the long-feuding bands. In July, Megadeth was added as the opening act for Aerosmith's Get A Grip US tour, but due to contractual disputes, and on stage remarks made by Mustaine about Aerosmith's "advancing" age, Megadeth was removed from the tour after just seven dates.

Following their canceled US tour, Megadeth returned to the studio to record "99 Ways to Die", a song that appeared on The Beavis and Butt-Head Experience, a compilation album featuring songs intercut with commentary by Beavis and Butt-head, released in November 1993. The song was later nominated for a Grammy in 1995 for Best Metal Performance.