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.
Australia competed at the 2004 Summer Olympics in Athens, Greece from 13 to 29 August 2004. Australian athletes have competed in every Summer Olympic Games of the modern era. The Australian Olympic Committee sent a total of 470 athletes to the Games to compete in 29 sports.
Egypt, represented by the Egyptian Olympic Committee, competed at the 2004 Summer Olympics in Athens, Greece from 13 to 29 August 2004. 97 competitors, 81 men and 16 women, took part in 48 events in 17 sports. Egypt's anthem, Bilady, Bilady, Bilady was played when Egypt won a gold medal.
Kazakhstan competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third appearance at the Summer Olympics in the post-Soviet era.
Italy competed at the 2004 Summer Olympics in Athens, Greece, from the 13th to the 29th of August 2004. The country has competed at every Summer Olympic games in the modern era, except for the 1904 Summer Olympics in St. Louis. The Italian National Olympic Committee sent the nation's largest ever delegation in history to the Games. A total of 364 athletes, 229 men and 135 women, competed in 27 sports.
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.
New Zealand competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's twenty-second appearance at the Olympics since its debut in 1908 as part of Australasia. The New Zealand Olympic Committee sent a total of 148 athletes, 81 men, and 67 women to the Games to compete in 18 sports, surpassing a single athlete short of the record from Sydney four years earlier. Basketball and field hockey were the only team-based sports in which New Zealand had its representation at these Olympic Games. There was only a single competitor in archery, boxing, and fencing.
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.
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.
Serbia competed at the 2008 Summer Olympics in Beijing, People's Republic of China. The country returned under the name Serbia after 96 years, previously competing under the names Yugoslavia (1920–1988), Independent Olympic Participants (1992), Yugoslavia (1996–2002) and Serbia and Montenegro (2004–2006).
Serbia competed at the 2012 Summer Olympics in London. This was the nation's third appearance at the Summer Olympics.
Montenegro competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's second appearance at the Summer Olympics.
The United States of America (USA) competed at the 2004 Summer Olympics in Athens, Greece. 533 competitors, 279 men and 254 women, took part in 254 events in 31 sports.
Serbia competed at the 2016 Summer Olympics in Rio de Janeiro, Brazil, from 5 to 21 August 2016. It was the nation's fourth appearance at the Summer Olympics as an independent country. The Olympic Committee of Serbia confirmed a roster of 103 athletes, 58 men and 45 women, to compete across 14 sports at the Games.
Montenegro competed at the 2016 Summer Olympics in Rio de Janeiro, Brazil, from 5 to 21 August 2016. This was the nation's third consecutive appearance at the Summer Olympics since it gained independence from Serbia in 2006.
Montenegro competed at the 2020 Summer Olympics in Tokyo. Originally scheduled to take place from 24 July to 9 August 2020, the Games were postponed to 23 July to 8 August 2021, because of the COVID-19 pandemic. It was the nation's fourth consecutive appearance at the Summer Olympics since gaining independence in 2006.
Yugoslavia (1920–1992 W)
Independent Olympic Participants (1992 S)
Montenegro (2008–)
Serbia (1912, 2008–)
Kosovo (2016–)
