"Forget Domani" is a song introduced in the 1964 film The Yellow Rolls-Royce being a composition by Riz Ortolani, who scored the film, and lyricist Norman Newell.

The song's theme of forgetting domani — Italian for "tomorrow" — is relevant to each of the three segments that comprise the storyline of The Yellow Rolls-Royce as each deals with lovers whose trysts involve a disregard for consequences, and the tune of the chorus of "Forget Domani" is incorporated in the theme song that plays underneath the film's opening credits. Otherwise, "Forget Domani" is heard only in the film's second segment set in Italy circa 1940 and focused on the dalliance between the gun moll (Shirley MacLaine) of an American gangster (George C. Scott) with a local tourist photographer (Alain Delon). The vocal version of "Forget Domani", credited to veteran Italian vocalist Katyna Ranieri who was Ortolani's wife, is seen performed by a singer in a tavern. The tune of "Forget Domani" is also heard as background music during a key love scene between the MacLaine/Delon characters set in the "Sapphire Grotto".

The Golden Globe winner for Best Original Song, "Forget Domani" did not receive a corresponding Academy Award nomination.

The Yellow Rolls-Royce was an MGM production and MGM Records issued singles of both a vocal version of "Forget Domani" by Katyna Ranieri and an instrumental version — subtitled "(Forget Tomorrow)" — by Riz Ortolani & His Orchestra in the UK in December 1964, the film The Yellow Rolls Royce having its UK premiere on December 31, 1964.

On January 22, 1965, MGM Record's top vocalist Connie Francis — whose Italian heritage was a key component of her public persona — cut "Forget Domani" in a Hollywood CA recording session produced by Danny Davis: the arranger was Don Costa. Francis' version of "Forget Domani" had a UK single release in February 1965: however Francis concurrent US single release was another track from her January 22, 1965 recording session: "For Mama", with "Forget Domani" being afforded its US single release subsequent to the May 13, 1965 US premiere of the film The Yellow Rolls Royce. While the UK single release of Francis' "Forget Domani" had featured the track "No Better Off" as B-side, for its US single release Francis' "Forget Domani" featured as B-side the track "No One Ever Sends Me Roses"; in its Australian single release Francis' "Forget Domani" was coupled with "For Mama".

Frank Sinatra, who, like Francis, was an American singer of Italian descent — recorded "Forget Domani" in a May 6, 1965 session at United Western Recorders in Hollywood produced by Jimmy Bowen and arranged by Ernie Freeman; the orchestra was conducted by Donnie Lanier. Sinatra cut the song a week before the US premiere of The Yellow Rolls-Royce which occurred May 13, 1965.

Both Connie Francis' and Frank Sinatra's "Forget Domani" singles debuted on the Hot 100 in Billboard dated June 26, 1965, at respectively number 95 (Francis) and number 100 (Sinatra), and over the next six weeks both singles made slight roughly equal chart ascents to peak on the Hot 100 dated July 31, 1965, at respectively number 78 (Sinatra) and number 79 (Francis): both singles charted for one subsequent week for a total Hot 100 run of seven weeks. Billboard's Easy Listening chart afforded the Connie Francis and Frank Sinatra "Forget Domani" singles respective peaks of number 16 and number 13.

"Forget Domani" was a number-one hit in South Africa for Connie Francis.