Chile competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.
Slovakia 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 since the post-Czechoslovak era. The Slovak Olympic Committee sent a total of 64 athletes to the Games, 48 men and 16 women, to compete in 11 sports. There was only a single competitor in artistic and trampoline gymnastics and sailing.
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.
Switzerland competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Swiss athletes competed at every Summer Olympic Games in the modern era, except when they boycotted the 1956 Summer Olympics in Melbourne as a protest to the Soviet invasion of Hungary. The Swiss Olympic Association sent a total of 98 athletes to the Games, 59 men and 39 women, to compete in 18 sports.
Finland competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. The nation has competed at every Summer Olympic Games since its official debut in 1908. The Finnish Olympic Committee sent a total of 56 athletes to the Games, 29 men and 27 women, to compete in 14 sports. There was only a single competitor in artistic gymnastics, taekwondo, weightlifting and tennis.
France competed at the 2012 Summer Olympics in London, between 27 July and 12 August 2012. French athletes have competed in every Summer Olympic Games of the modern era. The French Olympic Committee sent a total of 330 athletes to the Games, 183 men and 147 women, to compete in 24 sports.
Lithuania competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's eighth appearance at the Summer Olympics. The National Olympic Committee of Lithuania sent a total of 62 athletes to the Games, 39 men and 23 women, to compete in 14 sports. Men's basketball was the only team-based sport in which Lithuania had its representation in these Olympic games.
Iran competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. The nation has competed at every Summer Olympic games since its return in 1948, after having made their debut in 1900, with the exception of the 1980 and 1984 Summer Olympics. The National Olympic Committee of the Islamic Republic of Iran sent the nation's second-largest delegation to the Games, one less than it sent to Beijing. A total of 53 athletes, 45 men and 8 women, competed in 14 sports. This was also the youngest delegation in Iran's Olympic history, with half the team under the age of 25, and many of them are expected to reach their peak in time for the 2016 Summer Olympics in Rio de Janeiro. Heavyweight boxer Ali Mazaheri was the nation's flag bearer at the opening ceremony.
Belgium competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. The Belgian Olympic Committee sent the nation's largest delegation to the Games since 1976. A total of 119 athletes, 75 men and 44 women, competed in 16 sports. There was only a single competitor in slalom canoeing, BMX cycling, equestrian dressage, rowing, shooting, table tennis, and weightlifting. Field hockey was the only team event in which Belgium was represented at these Olympic games.
Italy competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This nation 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 smallest delegation to the Games since the 1988 Summer Olympics in Seoul. A total of 285 athletes, 162 men and 123 women, competed in 22 sports.
Poland competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's twentieth appearance at the Summer Olympics, having missed the 1984 Summer Olympics in Los Angeles because of the Soviet boycott. The Polish Olympic Committee sent a total of 218 athletes to the Games, 130 men and 88 women, to compete in 22 sports.
Hungary competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. 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 the nation's smallest delegation to the Games since 1956 to London. A total of 159 athletes, 97 men and 62 women, competed in 18 sports.
Kazakhstan competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's fifth appearance at the Summer Olympics in the post-Soviet era.
Ukraine competed at the 2012 Summer Olympics in London, from July 27 to August 12, 2012. This was the nation's fifth consecutive appearance at the Summer Olympics in the post-Soviet era. The National Olympic Committee of Ukraine sent a total of 238 athletes, split equally between men and women, to compete in 21 sports.
Austria competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. The nation has competed at every edition of Summer Olympic Games, except the 1920 Summer Olympics in Antwerp. The Österreichisches Olympisches Comité sent a total of 70 athletes to the Games, 39 men and 31 women, to compete in 17 sports. This was approximately the same size as the previous Games, with the difference of one male athlete, the addition of one female athlete and three sporting events participated in. There was only a single competitor in eventing, fencing, rhythmic gymnastics, modern pentathlon, and Greco-Roman wrestling.
Serbia competed at the 2012 Summer Olympics in London. This was the nation's third appearance at the Summer Olympics.
Slovakia competed in the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's fifth consecutive appearance at the Summer Olympics. The Slovak Olympic Committee sent a total of 47 athletes to the Games, 26 men and 21 women, to compete in 11 sports. There was only a single competitor in badminton, judo, triathlon, and weightlifting.
Cuba competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's nineteenth appearance in the Olympics. With baseball's removal from the Olympic program and the absence of the nation's volleyball team for the first time, the Cuban Olympic Committee sent the nation's smallest delegation to the Games since 1964. A total of 111 athletes, 66 men and 45 women, competed in 13 sports. There was only a single competitor in archery and table tennis.
Portugal competed at the 2012 Summer Olympics, held in London, from 27 July to 12 August 2012. The nation celebrated its centennial anniversary participating in the Olympics, having participated at every Summer edition since 1912. The Olympic Committee of Portugal sent a total of 77 athletes to the Games, 45 men and 32 women, to compete in 13 sports. Despite having the same number of athletes as in Beijing, Portugal did not qualify any athletes in archery, fencing and taekwondo.
Greece competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. The Hellenic Olympic Committee sent a total of 103 athletes to the Games in London, 65 men and 38 women, to compete in 19 sports. Men's water polo was the only team event in which Greece was represented at these Olympic Games.
Austria (1912)
Yugoslavia (1920–1988)
