Greece was the host country for the 2004 Summer Olympics in Athens, from 13 to 29 August 2004. As the progenitor nation and in keeping with tradition, Greek athletes have competed at every Summer Olympics in the modern era, alongside Australia, Great Britain, and Switzerland. The Hellenic Olympic Committee fielded a total of 426 athletes to the Games, 215 men and 211 women, and had achieved automatic qualification places in all sports, with the exception of men's and women's field hockey. It was also the nation's largest team ever in Summer Olympic history since the first modern Games were held in 1896.
Puerto Rico competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fifteenth consecutive appearance at the Olympics.
France competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. French athletes have competed in every Summer Olympic Games of the modern era. The French Olympic Committee sent a total of 308 athletes to the Games, 195 men and 113 women, to compete in 25 sports.
Ukraine competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Summer Olympics in the post-Soviet era. The National Olympic Committee of Ukraine sent the nation's largest ever delegation to these Games. A total of 240 athletes, 125 men and 115 women, took part in 21 sports. Women's handball was the only team-based sport in which Ukraine had its representation at these Games for the first time. There was only a single competitor in modern pentathlon and taekwondo.
Germany competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fourth consecutive appearance at the Summer Olympics after its reunification in 1990. The German Olympic Sports Confederation sent the nation's second largest delegation to the Games since its reunification. A total of 441 athletes, 250 men and 191 women, competed in 27 sports, and were nominated by DOSB at four occasions.
Russia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Summer Olympics as an independent nation. The Russian Olympic Committee sent a total of 446 athletes to the Games, 244 men and 202 women, to compete in all sports, except baseball, field hockey, football, and softball.
China competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's ninth appearance at the Summer Olympics since its debut in 1952. A total of 384 Chinese athletes, 136 men and 248 women, were selected by the Chinese Olympic Committee to compete in 28 sports. For the third time in its Olympic history, China was represented by more female than male athletes.
Spain competed at the 2004 Summer Olympics in Athens, Greece, from August 13 to 29, 2004. This nation has competed in every Summer Olympic Games since its official debut in 1920. Spain, however, boycotted two editions, the 1936 Summer Olympics in Nazi Germany, and the 1956 Summer Olympics in Melbourne when it joined the Dutch-led boycott, as a protest to the Soviet invasion of Hungary. The Spanish Olympic Committee sent the nation's third largest delegation in history to the Games. A total of 317 athletes, 177 men and 140 women, competed in 26 sports.
South Korea competed at the 2004 Summer Olympics in Athens, from 13 to 29 August 2004. This was the nation's fourteenth appearance at the Olympics, attending every Summer Olympics held during the country's existence up to that point with the exception of the 1980 Summer Olympics in Moscow because of its support for the United States-led boycott. The Korean Olympic Committee sent the nation's smallest delegation to the Games since 1992. A total of 264 athletes, 145 men and 119 women, competed in 25 sports.
The Netherlands competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Dutch athletes have competed in every Summer Olympic Games since its official debut in 1908. Netherlands, however, boycotted the 1956 Summer Olympics in Melbourne, because of the Soviet invasion of Hungary. The Netherlands National Olympic Committee sent a total of 210 athletes to the Games, 134 men and 76 women, to compete in 21 sports. Baseball, field hockey, and men's volleyball were the only team-based sports in which the Netherlands had its representation at these Games. There was only a single competitor in women's fencing.
Denmark competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.
Slovenia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fourth consecutive appearance at the Summer Olympics since the post-Yugoslav era. The Slovenian Olympic Committee sent the nation's largest ever delegation to the Games in Olympic history. A total of 79 athletes, 56 men and 23 women, competed in 10 sports. For the second consecutive time, men's handball was the only team-based sport in which Slovenia had its representation at these Games.
Hungary competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Hungarian athletes have competed at every Summer Olympic Games in the modern era, except the 1920 Summer Olympics in Antwerp, and the 1984 Summer Olympics in Los Angeles because of the Soviet boycott. The Hungarian Olympic Committee sent a total of 209 athletes to the Games, 119 men and 90 women, to compete in 20 sports. Water polo and handball were the only team-based sports in which Hungary had its representation in these Olympic Games. There was only a single competitor in road cycling and mountain biking.
Argentina competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's twenty-first appearance at the Olympic Games, except for three different editions. Argentina did not attend the 1904 Summer Olympics in St. Louis, the 1912 Summer Olympics in Stockholm, and the 1980 Summer Olympics in Moscow, because of its support for the United States-led boycott. The sailor Carlos Espínola was the nation's flag bearer at the opening ceremony. 152 competitors, 106 men and 46 women, took part in 86 events in 22 sports.
Angola competed at the 2004 Summer Olympics in Athens, Greece from 13 to 29 August 2004.
Serbia and Montenegro competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Previously known as the Federal Republic of Yugoslavia, this was the nation's third and last joint appearance at the Summer Olympics before Serbia and Montenegro became separated independent states in 2006. The Olympic Committee of Serbia and Montenegro sent a total of 85 athletes to the Games, 78 men and 7 women, to compete in 14 sports. Men's basketball, football, volleyball, and water polo were the only team-based sports in which Serbia and Montenegro had its representation at these Games. There was only a single competitor in road cycling, judo, tennis, and wrestling.
Croatia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fourth consecutive appearance at the Summer Olympics since the post-Yugoslav era. The Croatian Olympic Committee sent the nation's smallest delegation to the Games since its debut in 1992. A total of 81 athletes, 66 men and 15 women, competed in 14 sports. Men's water polo, and men's handball were the only team-based sports in which Croatia had its representation in these Olympic Games.
Tunisia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's eleventh appearance at the Olympics, except the 1980 Summer Olympics in Moscow because of its partial support to the United States boycott.
Lithuania competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's sixth appearance at the Summer Olympics. The National Olympic Committee of Lithuania sent the nation's smallest delegation to the Games since the 1992 Summer Olympics in Barcelona. A total of 59 athletes, 47 men and 12 women, competed in 13 sports, including the men's basketball team as the nation's team-based sport.
Tunisia competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's thirteenth appearance at the Olympics, having missed the 1980 Summer Olympics in Moscow because of its partial support for the United States boycott.
