In baseball, a home run occurs when the ball is hit in such a way that the batter is able to circle the bases and reach home safely in one play without any errors being committed by the defensive team in the process. In modern baseball, the feat is typically achieved by hitting the ball over the outfield fence between the foul poles (or making contact with either foul pole) without first touching the ground, resulting in an automatic home run. There is also the "inside-the-park" home run where the batter reaches home safely while the baseball is in play on the field.

Eighteen players have hit four home runs in a single Major League Baseball (MLB) game, which writers of Sporting News described as "baseball's greatest single-game accomplishment". The most recent to accomplish the feat to date is J. D. Martinez with the Arizona Diamondbacks against the Los Angeles Dodgers on September 4, 2017. No player has done this more than once in his career. In the pre-professional era, Lipman Pike also hit five home runs in 1866. No player has ever hit four home runs in a postseason game; that record is three, first accomplished by Babe Ruth in Game 4 of the 1926 World Series.

According to the Society for American Baseball Research, Oil Cities catcher Jay J. Clarke went 8–8 with eight home runs, a single-game professional record. However, Clarke's total is disputed, reported by some newspapers as three homers and eight runs scored, but there is no surviving box score to help confirm or deny his feat.

Bobby Lowe was the first to hit four home runs in a single game, doing so on May 30, 1894, for the Boston Beaneaters. Fans were reportedly so excited that they threw $160 in silver coins ($5,600 today) onto the field after his fourth home run. Of all players to achieve the feat, Lowe hit the fewest career home runs, with a total of 71. Two years after Lowe's feat, Ed Delahanty of the Philadelphia Phillies became the second player to hit four home runs in a game. Two other Phillies players have achieved the feat, Chuck Klein in 1932 and Mike Schmidt in 1976. Two other current franchises, the Atlanta Braves (with three) and the Los Angeles Dodgers (with two), have had multiple four-homer games in their history and share the distinction of having one four-homer game in each city they have called home (for the Braves, Boston, Milwaukee, and Atlanta; for the Dodgers, Brooklyn and Los Angeles). Five current franchises – the Braves, Baltimore Orioles, Chicago Cubs, Cincinnati Reds, and Oakland Athletics – share the record of having surrendered two four-homer games over their histories. Thirteen of the 30 franchises (as of 2021) have achieved at least one four-homer game, and 12 franchises have surrendered at least one. Eleven have never been involved in a four-homer game at all, although only three of these (Boston Red Sox, Detroit Tigers, Minnesota Twins) date back to before the 1960s expansion era.

Despite Delahanty's achievement on July 13, 1896, the Phillies lost to the Chicago Colts, one of only two occasions when a player hit four home runs but was on the losing team. The other such occasion took place in 1986, when Bob Horner had four home runs for the Braves, but the Montreal Expos emerged victorious. Following Delahanty's four-home run game in 1896, no other player would accomplish the feat for nearly 36 years, the longest gap between such occurrences. The shortest interval took place in 2002, when Mike Cameron hit his four on May 2, 2002, and Shawn Green repeated the feat 21 days later, on May 23. This was the first time two players had achieved a four-homer game in the same season; this would occur again in 2017 when Scooter Gennett and J. D. Martinez achieved the feat in June and September respectively. Cameron was also the first and only player to hit four solo home runs in one game, accounting for the minimum of 4 RBIs when accomplishing the feat. When Martinez struck his four home runs for the Arizona Diamondbacks against the Los Angeles Dodgers, he became the first player with a four-homer game to hit more homers than his opponents gained base hits.

These games have resulted in other MLB single-game records due to the extreme offensive performance. Mark Whiten tied Jim Bottomley for the most runs batted in in a single game with 12 in his four-homer game. Shawn Green hit a double and a single along with his four home runs for 19 total bases, an MLB record. It surpassed Joe Adcock's mark of 18, which also came from a four-homer game. Carlos Delgado is the only player to make four plate appearances in a game and hit a home run each time. Warren Spahn pitched the ball which Gil Hodges hit for the first of his four, the only Hall of Fame pitcher faced during a four-home-run game. Of the 14 players eligible for the Hall of Fame who have hit four home runs in a game, six have been elected. Players are eligible for the Hall of Fame if they have played in at least 10 major league seasons and have been either retired for five seasons or deceased for at least six months. These requirements leave three players ineligible who are living and have played in the past five seasons and one (Seerey) who did not play 10 seasons in MLB.

Player	Name
Date	Date of the game
Team	The player's team at the time
Opposing team	The team against whom the player hit four home runs
Score	Final score of the game, with the player's team's score listed first
RBI	The number of runs batted in the player had in the game
TB	The number of total bases the player had in the game
Career HR	The number of home runs the player hit in his MLB career
	The home runs were in consecutive plate appearances
†	Elected to the Baseball Hall of Fame
	MLB record
*	The player is still active.
‡	The player's team lost the game.

Players who have hit four home runs in a single regular-season game

Player	Date	Team	Opposing team	Score	RBI	TB	Career HR	Ref(s)
Bobby Lowe	May 30, 1894	Boston Beaneaters	Cincinnati Reds	20–11	9	17	71
Ed Delahanty†	July 13, 1896	Philadelphia Phillies	Chicago Colts	8–9‡	7	17	101
Lou Gehrig†	June 3, 1932	New York Yankees	Philadelphia Athletics	20–13	6	16	493
Chuck Klein†	July 10, 1936	Philadelphia Phillies	Pittsburgh Pirates	9–6	6	16	300
Pat Seerey	July 18, 1948	Chicago White Sox	Philadelphia Athletics	12–11	7	16	86
Gil Hodges†	August 31, 1950	Brooklyn Dodgers	Boston Braves	19–3	9	17	370
Joe Adcock	July 31, 1954	Milwaukee Braves	Brooklyn Dodgers	15–7	7	18	336
Rocky Colavito	June 10, 1959	Cleveland Indians	Baltimore Orioles	11–8	6	16	374
Willie Mays†	April 30, 1961	San Francisco Giants	Milwaukee Braves	14–4	8	16	660
Mike Schmidt†	April 17, 1976	Philadelphia Phillies	Chicago Cubs	18–16	8	17	548
Bob Horner	July 6, 1986	Atlanta Braves	Montreal Expos	8–11‡	6	16	218
Mark Whiten	September 7, 1993	St. Louis Cardinals	Cincinnati Reds	15–2	12^	16	105
Mike Cameron	May 2, 2002	Seattle Mariners	Chicago White Sox	15–4	4	16	278
Shawn Green	May 23, 2002	Los Angeles Dodgers	Milwaukee Brewers	16–3	7	19	328
Carlos Delgado	September 25, 2003	Toronto Blue Jays	Tampa Bay Devil Rays	10–8	6	16	473
Josh Hamilton	May 8, 2012	Texas Rangers	Baltimore Orioles	10-3	8	18	200
Scooter Gennett	June 6, 2017	Cincinnati Reds	St. Louis Cardinals	13–1	10	17	87
J. D. Martinez	September 4, 2017	Arizona Diamondbacks	Los Angeles Dodgers	13–0	6	16	315

Note: RBI and TB counts include all plate appearances the player had in the game.
Source:

Only one player has ever hit four home runs in a spring training game: Henry Rodriguez of the Los Angeles Dodgers against the New York Mets on April 24, 1995.

• MON@ATL: Bob Horner hits his fourth home run of game Archived 2020-11-23 at the Wayback Machine from MLB via YouTube
• STL@CIN: Whiten blasts four dingers, drives in 12 Archived 2020-04-04 at the Wayback Machine from MLB via YouTube
• SEA@CWS: Cameron hits four homers in the game Archived 2020-11-08 at the Wayback Machine from MLB via YouTube
• Green has monster day at the plate Archived 2020-09-05 at the Wayback Machine from MLB via YouTube
• TB@TOR: Delgado blasts four homers in the game Archived 2020-04-14 at the Wayback Machine from MLB via YouTube
• TEX@BAL: Hamilton goes 5-for-5 with four homers Archived 2020-03-19 at the Wayback Machine from MLB via YouTube
• Gennett and Martinez both hit 4 homers in a game Archived 2020-10-02 at the Wayback Machine from MLB via YouTube