Knock (French title: Knock ou le Triomphe de la médecine) is a 1923 French satirical play about hypochondria, written by Jules Romains. It was performed for the first time at the Théâtre des Champs-Élysées in Paris on 15 December 1923 in a production by Louis Jouvet.
The ambitious Dr. Knock arrives in a rural village , Saint-Maurice, to step into Dr. Parpalaid's footsteps as the local physician. Unfortunately all villagers are in good health, which makes Knock realize that he has been duped by Parpalaid. He therefore decides to make everybody believe they are actually far more sick then they actually are...
Titled Dr. Knock, the play was presented at the Peacock Theatre in Dublin in 1932, with set designs by the 16-year-old Orson Welles.
A British television version for the BBC's Theatre 625 series was broadcast in 1966.