She was forged in a foremost job in the sci-fi film Fantastic Voyage (1966), in which she portrayed a member of a healthcare team that is miniaturized and injected into the entire body of an wounded diplomat with the mission to help save his lifestyle. The film raised Welch's stature as a leading sex symbol of the period. The similar year, she appeared in the movie Sex Quartet (1966) as Elena in the segment "Fata Elena".