Slayer's previous album, Show No Mercy, became Metal Blade Records' highest selling release, selling 40,000 copies worldwide; the success led producer Brian Slagel to want to record another album with them. Slagel hired producer Ron Fair, who worked for Chrysalis Records, and had seen the band perform live and enjoyed their performance. On seeing Slayer in the studio, Fair stated, "Wow, these guys are really angry," as he was inexperienced working with heavy metal musicians. Slagel financed the album, in stark contrast to Show No Mercy, which was financed by singer Tom Araya, who used his earnings as a respiratory therapist, and a loan from guitarist Kerry King's father.
The budget organized by Slagel allowed for professional assistance. Bernie Grundman provided audio mastering, Eddy Schreyer worked on remastering, and Bill Metoyer, who worked on the band's earlier release Haunting the Chapel, acted as sound engineer. The recording featured audio effects such as the intro to "Hell Awaits", a reversed recording of a demonic-sounding voice repeating "Join us", ending with "Welcome back". Still, Araya later stated the album had poor production quality: "Nowadays, production-wise, it's so under par. But for what it was at the time, those are amazing records to me. I guess we could go in and redo it. But why ruin it?"
Drummer Dave Lombardo, on the other hand, asserts the album was professionally done compared to Show No Mercy: "I didn't have to overdub the cymbals, and we had a really good engineer." Lombardo's favorite song is "At Dawn They Sleep", "because it was kind of slow and grungy, but then it had that double-bass part at the end." While recording the track, neither guitarists King or Jeff Hanneman who wrote the lyrics were in the studio—only Araya and Slagel. On reading the lyrics, which featured a misspelled word, Araya sang it as it was spelled, although it's not a real word. The song "Hardening of the Arteries" on the album ends with a very similar section that makes up the beginning of the song "Hell Awaits" and is also one of the only Slayer songs to fade out on a continuous riff.