Extra innings is the procedure by which a tie is broken in the sport of baseball.

Ordinarily, a baseball game consists of nine innings, each of which is divided into halves: the visiting team bats first, after which the home team takes its turn at bat. However, if the score remains tied at the end of nine complete innings, the rules provide that "play shall continue until (1) the visiting team has scored more total runs than the home team at the end of a completed inning; or (2) the home team scores the winning run in an uncompleted inning." Because they bat in the second (or "bottom") half of an inning, a home team which scores to take a lead either in the ninth inning or at any point in extra innings automatically wins the game.

The rules of the game, including the batting order, availability of substitute players and pitchers, etc., remain intact in extra innings. Managers must display caution to avoid using all their substitute players, in case the game reaches extensive extra innings.

The record for most innings ever played in a single professional game is 33. On April 18, 1981, the Pawtucket Red Sox hosted the Rochester Red Wings in an International League game at McCoy Stadium in Pawtucket, Rhode Island. The game started an hour late due to failure of a light stanchion. The game was suspended at 4:07 a.m. April 19 after 32 innings, with the score tied 2-2, upon the league president's notifying the umpires of a league rule stating that no inning should begin after 12:50 a.m. On June 23 the game was completed, and Dave Koza's RBI single off Cliff Speck in the bottom of the 33rd inning gave Pawtucket a 3-2 victory. The official time to play the game was 8 hours 25 minutes, also a professional record.

The longest game by innings in Major League Baseball was a 1-1 tie in the National League between the Boston Braves and Brooklyn Dodgers in 26 innings, at Braves Field in Boston on May 1, 1920.

The longest American League game, and the longest major league game by innings which ended with one team winning, was a 7-6 victory by the Chicago White Sox over the Milwaukee Brewers in 25 innings, at Comiskey Park in Chicago in 1984. The game was begun at 7:30 p.m. on the evening of May 8, and after scoring early runs both teams scored twice in the 8th inning; but the game was suspended after 17 innings with the score tied 3-3 due to a league rule prohibiting an inning from beginning after 12:59 a.m. The game was continued the following evening, May 9, and both teams scored three times in the 21st inning to make the score 6-6; finally, in the bottom of the 25th, the White Sox' Harold Baines hit a home run to end the contest. Tom Seaver was the winning pitcher in relief. (A regularly scheduled game followed, meaning both nights saw 17 innings played; Seaver also started, and won, the second game.) The official time of the entire 25-inning game was 8 hours 6 minutes, also a major league record. [1]