The Indianapolis Colts own the longest winning streak in NFL history - 23 games. The streak began on November 2, 2008 with a victory over the New England Patriots and continued until a loss to the New York Jets on December 27, 2009. This game also ending the Colts' chance at an undefeated season, but the Colts did go on to win the AFC Championship (17-30) verses the Jets.
Note: The NFL excludes exhibition games and playoff games from their official statistics.
The 1972 Miami Dolphins, the first team in NFL history to go through a single season undefeated and the only team to have a perfect season including a Super Bowl victory, lost their second game of the 1973 regular season and wound up with a winning streak of 18 games.