If It's Tuesday, This Must Be Belgium is a 1969 American DeLuxe Color romantic comedy film made by Wolper Pictures and released by United Artists. It was directed by Mel Stuart, was filmed on location throughout Europe, and features many cameo appearances from various stars. The film stars Suzanne Pleshette, Ian McShane, Mildred Natwick, Murray Hamilton, Sandy Baron, Michael Constantine, Norman Fell, Peggy Cass, Marty Ingels, Pamela Britton, and Reva Rose.