[3] While vacationing in Hollywood at the age of 18, Tiffin visited the Paramount Pictures lot and was spotted by producer Hal B. Wallis, who arranged for her to take a screen test.

[5] She earned a Golden Globe nomination for each of her first two films,[6] She won the leading role in the Twentieth Century-Fox musical remake State Fair (1962), in which she was played Bobby Darin's love interest.

She appeared as a guest star on The Fugitive and filmed a television pilot for Fox titled Three in Manhattan that did not materialize into a series.

Tiffin costarred with Burt Lancaster in the 1965 Western The Hallelujah Trail and appeared in a segment of Kiss the Other Sheik (1965) that was filmed in Italy.

"[3] She appeared in The Almost Perfect Crime (1966) with Philippe Leroy; The Protagonists (1968); Torture Me But Kill Me with Kisses (1968), a hugely popular comedy; and The Archangel (1969) with Vittorio Gassman.

She appeared in her first American film in two years when she played a liberal college student and the love interest to Peter Ustinov in the comedy Viva Max!

(1973) and Brigitte, Laura, Ursula, Monica, Raquel, Litz, Florinda, Barbara, Claudia, e Sofia le chiamo tutte... anima mia (1974).