OSN Saturn (ОСН Сатурн УФСИН России по г. Москве; Otdel Spetsialnogo Naznacheniya Saturn) is the Moscow department of the Federal Penitentiary Service (FSIN) special purpose unit (police tactical unit).

Saturn was formed in April 1992 as a part of the Moscow Department of Punishment Execution (UIN) under the Ministry of the Interior.

In 2006, the UIN system (including all regional departments and special purpose units) was renamed the Federal Penitentiary Service, and was moved from the jurisdiction of the Ministry of Interior to the Russian Ministry of Justice.

In summer 2000, Saturn officers protected PACE delegates during their visit to the Chechen Republic.

Saturn participated in the hostage rescue operation in Kapotnya investigative isolation ward No.