The first four radio episodes were adapted for a new double LP, also entitled The Hitchhiker's Guide to the Galaxy (appended with "Part One" for the subsequent Canadian release), first by mail-order only, and later into stores. The double LP and its sequel were originally released by Original Records in the United Kingdom in 1979 and 1980, with the catalogue numbers ORA042 and ORA054 respectively. They were first released by Hannibal Records in 1982 (as HNBL 2301 and HNBL 1307, respectively) in the United States and Canada, and later re-released in a slightly abridged edition by Simon & Schuster's Audioworks in the mid-1980s. Both were produced by Geoffrey Perkins and featured cover artwork by Hipgnosis.
The script in the first double LP very closely follows the first four radio episodes, although further cuts had to be made for reasons of timing. Despite this, other lines of dialogue that were indicated as having been cut when the original scripts from the radio series were eventually published can be heard in the LP version. The Simon & Schuster cassettes omit the Veet Voojagig narration, the cheerleader's speech as Deep Thought concludes its seven-and-one-half-million-year programme, and a few other lines from both sides of the second LP of the set.
Most of the original cast returned, except for Susan Sheridan, who was recording a voice for the character of Princess Eilonwy in The Black Cauldron for Walt Disney Pictures. Cindy Oswin voiced Trillian on all three LPs in her place. Other casting changes in the first double LP included Stephen Moore taking on the additional role of the barman, and Valentine Dyall as the voice of Deep Thought. Adams's voice can be heard making the public address announcements on Magrathea.
Because of copyright issues, the music used during the first radio series was either replaced, or in the case of the title it was re-recorded in a new arrangement. Composer Tim Souster did both duties (with Paddy Kingsland contributing music as well), and Souster's version of the theme was the version also used for the eventual television series.
The sequel LP was released, singly, as The Hitchhiker's Guide to the Galaxy Part Two: The Restaurant at the End of the Universe in the UK, and simply as The Restaurant at the End of the Universe in the USA. The script here mostly follows Fit the Fifth and Fit the Sixth, but includes a song by the backup band in the restaurant ("Reg Nullify and his Cataclysmic Combo"), and changes the Haggunenon sequence to "Disaster Area".
As the result of a misunderstanding, the second record was released before being cut down in a final edit that Douglas Adams and Geoffrey Perkins had both intended to make. Perkins has said, "[I]t is far too long on each side. It's just a rough cut. [...] I felt it was flabby, and I wanted to speed it up." The Simon & Schuster Audioworks re-release of this LP was also abridged slightly from its original release. The scene with Ford Prefect and Hotblack Desiato's bodyguard is omitted.
Sales for the first double-LP release were primarily through mail order. Total sales reached over 60,000 units, with half of those being mail order, and the other half through retail outlets. This is in spite of the facts that Original Records' warehouse ordered and stocked more copies than they were actually selling for quite some time, and that Paul Neil Milne Johnstone complained about his name and then-current address being included in the recording. This was corrected for a later pressing of the double-LP by "cut[ting] up that part of the master tape and reassembl[ing] it in the wrong order". The second LP release ("Part Two") also only sold a total of 60,000 units in the UK. The distribution deals for the USA and Canada with Hannibal Records and Simon and Schuster were later negotiated by Douglas Adams and his agent, Ed Victor, after gaining full rights to the recordings from Original Records, which went bankrupt.