Having already experimented with spoken word interludes on "Morning Glory" and "Late Lament" on Days of Future Passed, The Moody Blues tried the practice again on In Search of the Lost Chord, on the Graeme Edge-penned pieces "Departure" and "The Word". The latter was recited by Pinder, who was the primary reciter of Edge's poems on this and other Moody Blues albums. "Departure", which escalates from mumbling to hysterical laughter, is a rare studio example of Edge reciting his own words.
In Search of the Lost Chord was released on 26 July 1968. It peaked at number 5 in the UK and reached number 23 on the US album charts. Neither of the two singles from the album, "Ride My See-Saw" nor "Voices in the Sky", charted in the top 40 on the Billboard charts, although the latter reached number 27 on the UK singles chart.
In Search of the Lost Chord was remastered into SACD in March 2006 and repackaged into a 2-CD Deluxe Edition. Unlike the other Moody Blues albums released in Deluxe Editions at the time, this did not come with a new 5.1 surround sound mix as the original multitrack masters could not be found. In 2008 a remaster for single standard audio CD was issued with the nine bonus tracks.