Twenty-One was originally conceived by host Jack Barry and producing partner Dan Enright as a weekly half-hour program for CBS' 1956–1957 schedule. The show was ultimately picked up by NBC and ran from September 12, 1956, to October 9, 1958, under the sponsorship of Pharmaceuticals, Inc., the makers of Geritol. The series finished at #21 in the Nielsen ratings for the 1957–1958 season. In 1958, Elfrida von Nardroff won $220,500 on the game show Twenty-One, more money than any other contestant on the show. After starting the 1958–59 season with an 8:30 Thursday night time slot, Twenty-One ran on October 2 and on October 9 before being abruptly canceled. An announcement broadcast a few hours before the scheduled October 16 program informed viewers that it would not be seen. A spokesman for Pharmaceuticals said, "Twenty-One was dropped because of a decline in ratings. We must admit that the investigation had something do with this decline," after the October 9 show had the lowest rating in its history."Twenty-One' Quiz Dropped by N.B.C.— TV Show Under Scrutiny of Grand Jury Here Will Be Replaced by Sponsor", by Val Adams, The New York Times, October 17, 1958, p. 58 A prime-time version of Concentration was introduced in the 8:30 time slot on October 30, with Barry as the host and Pharmaceuticals' Geritol as the sponsor.
