21st Precinct, also known as Twenty-First Precinct and Twenty First Precinct, was a police drama radio show that aired on CBS from July 7, 1953, to July 26, 1956. The show was initially a summer replacement for My Friend Irma and was produced in cooperation with the Patrolmen's Benevolent Association of the City of New York. The series presented true criminal stories from a policeman's perspective, even though the 21st Precinct did not exist during the show's run.

The fictional precinct, however, was closely based on the Upper East Side's 23rd Precinct in Manhattan. Stanley Niss served as the producer, writer, and director, with Everett Sloane, James Gregory, and Les Damon playing the role of Captain Frank Kennelly. Other cast members included Ken Lynch as Lt. Matt King, Harold Stone as Sgt. Waters, and Santos Ortega as Lt. Gorman.

The show's opening and closing focused on the responsibility of the 21st Precinct officers in providing security for the people living and working within their jurisdiction. The series gained popularity after the success of Dragnet, as audiences were eager to learn about true-to-life police stories. While the events depicted in 21st Precinct were less gritty than in Dragnet, the show's stories highlighted the noble actions of everyday cops facing everyday challenges, making the world a safer place for their communities.