Deal or No Deal is an American version of the international game show of Dutch origin of the same name. The show is hosted by Howie Mandel, and premiered on December 19, 2005, on NBC. The hour-long show typically aired at least twice a week during its run, and included special extended or theme episodes. The show started its fourth season on August 25, 2008, a day after NBC's coverage of the 2008 Beijing Olympics ended. A daily syndicated half-hour version of the show debuted on September 8, 2008, and continued for two seasons.

The game is primarily unchanged from the international format: a contestant chooses one briefcase from a selection of 26. Each briefcase contains a cash value from $0.01 to $1,000,000. Over the course of the game, the contestant eliminates cases from the game, periodically being presented with a "deal" from The Banker to take a cash amount to quit the game. Should the contestant refuse every deal, they are given the chance to trade the case they chose at the outset for the only one left in play at the time; they then win the amount in the selected case.

Special variations of the game, including a "Million Dollar Mission" introduced in the third season, were also used, as well as a tie-in with a viewer "Lucky Case Game".

The show was a success for NBC, typically averaging from 10 to 16 million viewers each episode in the first season, although the subsequent seasons only averaged about 5–9 million viewers each episode. It has led to the creation of tie-in board, card, arcade, and video games, as well as a syndicated series played for smaller dollar amounts.

The show went on hiatus in early 2009, and its Friday night time slot was replaced with Mandel's other series Howie Do It. The network later announced that Deal or No Deal would return on May 4, 2009, to air its remaining episodes. These remaining four were taped in September 2008, and aired on three consecutive Mondays, May 4, 2009, May 11, 2009, and the final two on May 18, 2009.

On December 3, 2018, the show returned to NBC as a holiday special with original host Howie Mandel. New episodes of the program began airing on CNBC on December 5, 2018. The show aired its final episode on August 7, 2019.