In New York City it was not aired by the then all-news WCBS but by its originating station, WOR, which produced and announced it as simply Radio Mystery Theater.

The format was similar to that of classic old time radio shows like The Mysterious Traveler and The Whistler, in that the episodes were introduced by host E. G. Marshall who provided pithy wisdom and commentary throughout.

E. G. Marshall hosted the program from January 1974 until February 1, 1982, when actress Tammy Grimes took over for the remainder of the series' final season, maintaining the format.

Series listeners will immediately recognize the "RMT Theme" beginning about 1:35 on the "Two" soundtrack selection from the Twilight Zone CD boxed set.

[citation needed] Other background tracks from the Twilight Zone music library, to which CBS owned full rights, were featured repeatedly in episodes of CBSRMT.

The theme song and the other music was also previously used in the 1950s and 1960s in other CBS-owned radio and television dramas (Perry Mason; Rawhide; The Fugitive; Gunsmoke; Have Gun Will Travel; Suspense; Yours Truly, Johnny Dollar; etc.

These included a full week of stories by an American writer, (Edgar Allan Poe in 1975, Mark Twain in 1976); week-long adaptations of classic novels (The Last Days of Pompeii in 1980, Les Misérables in 1982); and original dramas about historical figures (Nefertiti in 1979, Alexander the Great in 1981).

Notable regulars included Mason Adams, Lloyd Battista, John Beal, Robert Dryden, Teri Keane, Ralph Bell, Howard Da Silva, Keir Dullea, Patricia Elliot, Morgan Fairchild, Bernard Grant, Veleka Gray, Jack Grimes, Fred Gwynne, Marian Hailey, Larry Haines, Paul Hecht, Celeste Holm, Russell Horton, Kim Hunter, Richard Kiley, Beatrice Straight, John Lithgow, Roberta Maxwell, Mercedes McCambridge, Kevin McCarthy, Arnold Moss, William Redfield, Tony Roberts, Norman Rose, Alexander Scourby, Marian Seldes, Kristoffer Tabori and Michael Tolan.

The series introduced a new generation of listeners to many of the great voices from radio's golden age , including Joan Banks, Jackson Beck, Virginia Gregg, Victor Jory, Mandel Kramer, Marvin Miller, Dan Ocko, Santos Ortega, Alan Reed, Rosemary Rice, Anne Seymour, Arnold Stang, Les Tremayne, Lurene Tuttle and Janet Waldo.

A number of well-known veteran and future stars of stage, film and TV made appearances, including: When the program began in 1974, actors were paid union scale; at the time around $73.92 per episode.

[citation needed] From June 3 to November 27, 1998, CBSRMT was rebroadcast over CBS radio affiliates and, in 2000, on some NPR stations, in both cases, Himan Brown re-recorded the original introduction and narrations of E.G. Marshall and Tammy Grimes.