This is the last Osbourne studio album to feature guitarist Randy Rhoads and drummer Lee Kerslake.

Although bassist Rudy Sarzo and drummer Tommy Aldridge are credited in the liner notes and pictured on the inner sleeve for the American vinyl and cassette release and later CD re-issues, it was bassist Bob Daisley and drummer Lee Kerslake who performed all bass and drum parts on the original release.

Kerslake claims to have also had a hand in the writing of the album, even performing lead vocals on some of the original demo recordings.

"[7] Although Don Airey is credited as keyboardist on the album, it was in fact a musician named Johnny Cook (who had worked with Daisley in Mungo Jerry in the 1970s) who actually recorded the keyboard parts.

[11][15] Steve Huey of AllMusic stated that "it's not uncommon to find fans who prefer Diary to Blizzard, since it sets an even more mystical, eerie mood, and since Rhoads' playing is progressing to an even higher level".

[16] Canadian journalist Martin Popoff called Diary of a Madman "a lasting classic that stands as the definitive showcase for Randy Rhoads.

J. D. Considine of Rolling Stone, for example, opined upon the album's original release that "the songs here are little more than riffs with a vocal line pasted on top" and referred to Rhoads as "a junior-league Eddie Van Halen – bustling with chops but somewhat short on imagination".

[17] The 2002 Diary of a Madman reissue was derided by fans due to the removal of Daisley and Kerslake's original bass and drum tracks.

The re-issue featured re-recorded bass and drum tracks contributed by Osbourne's then-bassist and drummer Robert Trujillo and Mike Bordin, respectively.

The move was suspected of being retaliatory in nature, as Daisley and Kerslake had successfully sued Osbourne and his wife/manager Sharon in court, winning songwriting credits and royalties for their contributions to Diary of a Madman.

In May 2011, Sony Legacy released its Deluxe 30th Anniversary Editions of Diary of a Madman and Blizzard of Ozz with the original bass and drum tracks.

[20] A box set was also released which included the remastered editions of both albums on CD as well as vinyl, and a DVD documentary entitled Thirty Years After The Blizzard.