* ''Radio/AmericanTop40'' has this in spades.
** The second episode of the original 1970-1995 series – aired July 11, 1970 – is missing the master tape for its third hour. Many years later, a de facto "third hour" was created featuring segments from shows aired in July and early August, 1970.
** The master recordings to ''Casey's Top 40'', the countdown program hosted by Creator/CaseyKasem from January 1989 to March 1998 (following his August 1988 departure from [=AT40=]), are completely ''gone'', according to the show's production company/rights holder Westwood One Radio Networks. Though the entire series circulates via vinyl[=/=]CD copies distributed to radio stations (and, as such, can be found on Website/YouTube), the episodes themselves have not been broadcast over any actual radio stations since their initial airing.
** Although all programs from the Shadoe Stevens-era (1988-1995) exist, they are not owned by Premiere Radio Networks, owners of the ''American Top 40'' franchise since 1998 (when they were known as AM[=/=]FM Radio Networks); instead, they are owned by Cumulus Media (successors to the show's original production company, Creator/{{ABC}} Watermark; interestingly, Cumulus now also owns Westwood One, owners of ''Casey's Top 40''). A video uploaded by Shadoe to his personal Website/YouTube account in 2015 suggested his episodes would soon be syndicated, but this still has yet to happen as of 2022.
* All episodes from [=AT40=]'s sister program, ''Radio/AmericanCountryCountdown'', are believed to exist in its entirety from the show's beginning (since 1973). With the exception of select shows from the 1990s, aired as part of the series ''ACC Rewind With Bob Kingsley'' (2015-2019), these shows have not been re-aired.
** All episodes from Kingsley's subsequent program, ''Radio/BobKingsleysCountryTop40'' (which he helmed from 2006 until his death in 2019), exist. Reruns began airing, starting with the debut program of January 7, 2006, on WSM-AM in Nashville, but were previously never re-aired.
* ''Tales by the Fireside'', a popular Creator/{{BBC}} world service radio programme of the narrator's (Lionel Marson M.C.) experiences as a soldier during both World War II and the Great War. Despite being effectively the voice of the BBC's world service, and thus Britain, during his time with the station, no copies of the programme are known to have survived to this day. Even the name of Lionel Marson is less than well known, due to his being active on air at a time when mentioning one's name while broadcasting was considered extremely poor form. At the time, he was simply recognised by his voice. This tradition was first broken only shortly before he retired.
** The current generations of his family are actively searching for recordings.
* Many of Creator/TheFiresignTheatre's live radio performances, such as their Hour Hour shows, contained music that was legal to broadcast live but means they can't be sold as aired. The official Firesign archivist is editing much of this material for just that reason.
* ''Radio Mystery Theater''.
* Radio/PaulHarvey's ''News and Comment'' and ''The Rest of the Story'' shows. His website used to have some archives, but the site was taken down after he died. Paulharveyarchives.com ''used'' to have several shows, but the site has been "in transition" for several years now.
* From 1986 through 2012 (plus a one-off in 2016), ''Radio/TheBobAndTomShow'' released albums that compiled popular recent skits, guest appearances, songs, etc. at the rate of at least one per year, as well as GreatestHitsAlbum-style compilations for particularly popular characters or topics. All of them went out of print within a few years and their topical nature rendered reissues out of the question, even more so for the collections made before the show went national in 1995, because they included many Indiana-specific skits/songs. Worse, two early titles (''A Day at the Race!'' and ''Good Morning Saudi Arabia'') were cassette-only releases. Also, sometime around 2022, the albums that are available on Apple Music were replaced with new releases of them, losing a few tracks in the process.
* Vivian Stanshall (late of The Bonzo Dog Doo Dah Band), made numerous [[Creator/TheBBC BBC]] radio sessions for the John Peel Show, featuring comic monologues and songs, mostly based on his "Rawlinson End" concept. There have since been an album, a book and a film of Rawlinson End, but although the BBC has released lots of other "Peel Sessions" on CD, Stanshall's remain in the vaults apart from the odd rare broadcast and bootlegs.
* The radio version of ''Literature/AnotherTimeAnotherPlace'' only seems to be available through the academic database Box of Broadcasts, which can only be accessed via British universities.
* Many compilation [=CD=]s of ''Radio/ImSorryIHaventAClue'' are available, but they don't feature the complete episodes. In particular, the earlier ones never contain Pick Up Song, which requires the team to sing along to a recording, due to the reproduction rights. Apparently, in 2010 something changed, and compilations from Volume 12 on ''do'' include it.
* All of George Orwells broadcasts from the BBC during the war are lost. Most of them were not seen as worth keeping and because of his wartime wound to the throat, he did not sound entirely radio friendly.
* Creator/BigFinish has had this happen twice. ''Series/TheTomorrowPeople'' had a series of audio dramas featuring the original 1970s cast. Five series of audios were released, and during production of the 6th series, their license was revoked and Big Finish had to remove all sales links from their site. A similar thing happened with their continuation of ''Series/SapphireAndSteel''.
* As the website's digital archives only go back four or five years, and only a few classic episodes are available in the Art Bell classic library (and this is all behind a paywall), Radio/CoastToCoastAM tape traders (and torrenters) are abundant, sharing mostly the Art Bell shows.