The 2003 Major League Baseball All-Star Game was the 74th midsummer classic between the all-stars of the American League (AL) and National League (NL), the two leagues constituting Major League Baseball, and celebrated the 70th anniversary of the inaugural All-Star Game played in Chicago, Illinois in 1933.

The game was held on July 15, 2003 at U.S. Cellular Field, the home of the Chicago White Sox of the American League. The game resulted in the American League defeating the National League 7–6, thus awarding an AL team (which was eventually the New York Yankees) home-field advantage in the 2003 World Series. This game was the first All-Star Game to award home-field advantage in the World Series to the winning league, a rule that stemmed from a controversial 7–7 tie in the previous year's edition. In the days leading up to the game, Fox advertised it with the tagline: "This time it counts." Subsequent editions altered the slogan to "This one counts" to reflect the new method of determining the World Series' home-field advantage; that arrangement ended with the 2016 edition, where the AL team (which became the Cleveland Indians, now the Cleveland Guardians) also won home-field advantage; the AL would win the next six years, as well as the last four. The winning league had a 9–5 record in the corresponding year's World Series, with the AL going 6–5 in the 11 years it won the All Star Game and the NL going 3–0 in the three years it won the All Star Game.

This All-Star Game marked the seventh All-Star appearance for the Naval Station Great Lakes color guard from Waukegan, Illinois, who this year was joined by police officers from the Kane County Sheriff's Department who presented the Canadian and American flags in the outfield. Both the five-man color guard and the sheriff's department officers accompanied Michael Bublé, who sang O Canada, and Vanessa Carlton, who sang The Star-Spangled Banner. Bublé's performance of "O Canada" was not televised until after the game in the Chicago area, while Carlton's performance was followed by fireworks that shot off the U.S. Cellular Field scoreboard. This was also the last All-Star game to have the stadium's public address announcer announce the all-star rosters and coaches; the game's play-by-play announcer (in this case, Joe Buck) proceeds that custom starting the next year's game and onwards.

Players in italics have since been inducted into the National Baseball Hall of Fame.

Notes

• ^a Player was unable to play due to injury.
• ^b Player was selected to start, but was unable to play due to injury.
• ^c Player replaced an injured player.
• ^FV Player was selected by the fans through the All-Star Final Vote.

• For the first time since 1978 (Reds: Pete Rose, Joe Morgan, and George Foster) an all-star team had the first three hitters from the same regular season team (Cardinals: Renteria, Edmonds, and Pujols).
• From 1997-July 1998, Jason Schmidt and Esteban Loaiza were teammates in Pittsburgh.
• The honorary captains for the game were Hall of Famers Gary Carter (N.L.) and Luis Aparicio (A.L.).
• This was Eric Gagné's only blown save of 2003, as he went a perfect 55 for 55 in save opportunities in the regular season.
• This was the first All-Star Game in which one of the managers was not the manager of the team he had taken to the World Series the year before. NL manager Dusty Baker had led the San Francisco Giants to the NL pennant in 2002, but during the offseason had left the Giants to become manager of the Chicago Cubs. Baker, and not his San Francisco replacement, Felipe Alou, still managed the team.

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