OSS 117: Lost in Rio (French: OSS 117 : Rio ne répond plus) is a 2009 French spy comedy film co-written and directed by Michel Hazanavicius. It is a sequel to Hazanavicius' OSS 117: Cairo, Nest of Spies (2006), and sees Jean Dujardin reprising his role as French secret agent Hubert Bonisseur de La Bath / OSS 117. Set in 1967, Lost in Rio sees OSS 117 sent to Brazil in order to retrieve a microfilm list of French Nazi sympathizers, only to once again unknowingly set foot into a bigger international intrigue.

Like the first film, Lost in Rio is based on the OSS 117 character from the novels by Jean Bruce, but acts as a parody rather than a faithful adaptation. The original title literally translates to OSS 117: Rio Doesn't Respond Anymore, a reference to the 1932 film F.P.1 Doesn't Respond. Lost in Rio received praise for its direction, humour, dialogues and performances. A sequel, OSS 117: From Africa with Love, directed by Nicolas Bedos, was released in 2021.